by Dmitry Vasiliev
07/30/2012 | 10:50 AM
Midrange power supply units are always in demand because users of entry-level PCs often want to have some reserve of wattage in case of potential upgrades whereas midrange PC configurations such PSUs are specifically designed for are always popular and widespread, too.
In this review of six midrange PSUs we'll take a look at two pairs of products from Antec and Chieftec and at one model from HIPRO and OCZ each. Notwithstanding comparable wattage ratings, the most expensive of them (Antec EarthWatts EA-650 Platinum) costs more than twice as much as the most affordable (HIPRO HP-D5201AW). So, there’s something to choose from and we are going to find out if you can save some money without sacrificing much in terms of product characteristics.
The following article offers a detailed description of our testing methodology and equipment and a brief explanation of what the specified and tested parameters of power supplies mean: X-bit Labs Presents: Power Supply Units Testing Methodology. If you feel overwhelmed with the numbers and terms this review abounds in, refer to the Methodology.
You can also go to our Cases/PSU section to check out reviews of all other PSU models we have tested in our labs.
We will mark the actual power consumption of three system configurations (discussed in our article PC Power Consumption: How Many Watts Do We Need?) in the cross-load diagrams. This will help you see if the tested PSU can meet the requirements of a real-life PC.
We already tested a lower-wattage model from this series. It was the Antec High Current Gamer HCG-520. The model we’re going to take a look now differs in wattage and also has an additional letter M in its name which refers to its modular design.
The packaging is somewhat different from the junior model’s, yet Antec's corporate mix of black and yellow is unmistakable.
The PSU comes in a pouch but the latter’s quality isn‘t high. The material is cheap and there are no strings to tie it up. The rest of the accessories are perfectly standard: a user guide, some fasteners, a mains cord, and detachable cables in a plastic pack.
Except for the detachable cables, the HCG-620M looks just like the previously tested HCG-520 with its black and red color scheme and angular fan grid with Antec logo.
On the back panel we can see an On/Off switch and a sticker with the PSU’s wattage rating and the manufacturer’s name. The word “Antec” is also pressed out in the metal of one of the side panels. The PSU case lacks any other vents save for the fan cutout and the honeycomb mesh in its back.
The HCG-620M turns out to be very much alike to the HCG-520 inside as well. It shares the same Seasonic S12-II Bronze platform (the modular cables might suggest the M12-II Bronze series but the latter has a split +12V rail and a different design of the modular connectors).
So, like its junior cousin, the HCG-620M features active PFC and lacks dedicated voltage regulation.
It’s got the same controllers, too: a PS223 supervisor and a PFC & PWM controller Infineon ICE1CS02. Both chips reside on daughter cards, one of which is near the mains connector and another, behind the large input capacitor.
The quality of assembly is high as is typical of Seasonic.
The PSU employs capacitors from United Chemi-Con which enjoy a blameless reputation.
There is also a single capacitor from Rubycon, whose reputation is brilliant as well, in the output circuitry.
The Antec High Current Gamer HCG-620M is equipped with the following cables and connectors:
The HDD connectors have one row of five pins whereas the PCIe/HDD connectors have two rows of five pins and, as their marking suggests, can be used for the power cables with SATA and PATA connectors, too.
Included with the PSU are:
So, the PSU offers a sufficient selection of cables which are all of adequate length. By the way, the CPU power cable of the HCG-620M is 5 centimeters longer than the original Seasonic’s, which can make a difference in a system case with bottom PSU bay.
Without any surprises the specifications coincide with those of the original 620-watt model of the Seasonic S12-II series. The specs are up to today’s requirements. The PSU can deliver over 90% of its full output power across the +12V rail while the load capacity of the +3.3V and +5V rails is limited to a rather modest level of 130 watts.
If you take a closer look at the specification block, you may notice a black sticker covering one of the certification icons. We couldn't help removing it:
The black sticker above one of the certification icons covers the Russian Rospromtest badge. The PSU series must have not yet passed that certification when this sample was manufactured.
Working together with our SmartUPS SC 620, this PSU was stable at loads up to 374 watts when powered by the mains but couldn’t switch to the UPS’s batteries even at 280 watts.
The most important +12V voltage is very stable for a PSU that lacks dedicated voltage regulation. Each of our three reference PC configurations is in the 1% zone. In fact, the +12V voltage is never going to deflect by more than 2% from its required level in the typical load range.
The +5V voltage is the most stable at low loads. That's no problem since this voltage is no more than 2% off the required level at loads up to 50 watts on the +5 and +3.3V rails combined. Most computers don’t need more than that today.
The +3.3V rail is somewhat less stable, its voltage being the closest to the required level when there's high load on each power rail. The +3.3V voltage is 3% off at medium loads and 4% off when the computer is idle. Fortunately, this is the least used voltage in modern PCs.
Summing everything up, the HCG-620M delivers stable voltages, considering that it lacks dedicated voltage regulation.
The high-frequency voltage ripple is low but there are occasional spikes on the +5V and +12V rails that shoot over the industry standard’s limits.
The same goes for the ripple at the double frequency of the mains, except that it’s now the +3.3V rather than the +5V rail that has occasional voltage spikes above the permissible limits.
In fact, this picture is similar to what we saw with the HCG-520 as well as with Seasonic’s original products.
The HCG-620M is cooled by a 135mm 9-blade fan ADDA ADN512MB-A90. A large part of its impeller is covered with a piece of transparent plastic to optimize air flows.
The fan starts out at 900 RPM and retains this speed until a load of 300 watts. Then it accelerates quickly and linearly, reaching 1000 RPM at 350 watts and becoming rather noisy at loads above 400 watts. The maximum speed of the fan, somewhat higher than 2000 RPM, is achieved at 560 watts, and the fan keeps this speed until full load.
Thus, the HCG-620M is rather quiet at low and medium loads, but gets noisier than most competitors at high loads.
The HCG-620M is 86.4%, 87.7% and 84.3% efficient at the reference loads of 20%, 50% and 100%, respectively. It meets the requirements of the 80 PLUS Bronze certification whose badge it carries by a good margin.
The peak efficiency of 88.1% could be observed at a load of 256 watts.
The power factor remains as high as 99% through the larger part of the load range, which is an excellent result.
The standby source does its job without a problem.
The HCG-620M is a rather high-efficiency PSU with stable voltages and handy modular cables. The only downside in the electrical department is that it occasionally has high spikes of voltage. It is also noisy at high loads.
This model from Antec has a slightly higher wattage rating than the previous one and lacks modular cables. Its key feature is efficiency, though. As its name suggests, the EA-650 Platinum meets the 80 PLUS Platinum specification whereas the HCG-620M is merely Bronze.
80 PLUS Platinum products used to be expensive until recently but the EA-650 Platinum costs just a little more than lower-efficiency PSUs of comparable wattage (but it lacks modular cables which are usually offered by comparably priced PSUs of lower efficiency).
The EA-650 Platinum is shipped in a taller box than its gaming series cousin while the corporate black of the front panel has become brighter, obviously to look more like platinum. The manufacturer tries to focus the customer's attention on the 80 PLUS Platinum certification as best he can.
The accessories include everything necessary: fasteners, a user manual, a mains cord, four mounting screws and two reusable cable straps. Also, the PSU comes with its cables already tied up with two plastic straps.
This model has a much more modest appearance than the HCG-620M. It’s got a punched-out vent grid, no modular cables, and Antec’s standard black-and-yellow coloring without the aggressive red of the gaming series.
There is no label on the back which enlivened the HCG-620M. The mains connector is oriented vertically.
There are no additional vents in the case (except for a small round hole near the cables whose purpose is a mystery to us).
Notwithstanding its high specified efficiency, the EA-650 Platinum has a rather roomy interior.
The actual maker can be identified easily. There are FSP-branded chips on both sides of the word Antec on the PCB: FSP6600 and FSP6601. And FSP only uses its chips in PSUs of FSP’s own manufacture.
In fact, the interior design is overall similar to FSP’s Aurum series.
Interestingly, despite its high efficiency (and, as you’ll see shortly, very stable voltages), the EA-650 Platinum doesn’t seem to have DC-DC converters or a third magnetic amplifier choke in the output area. In other words, it lacks dedicated voltage regulation.
Besides the two FSP-branded chips, there is a small daughter card with a Weltrend WT7579 supervisor in the output circuitry.
The PSU mostly uses Japanese capacitors from United Chemi-Con, but we also found a couple of Taiwanese CapXon components (one of them is the large barrel at the input).
The EA-650 Platinum is equipped with the following cables and connectors:
The EA-650 Platinum is close to the above-discussed HCG-620M in this respect. It just lacks the latter’s modular design and has fewer PATA power connectors which are not very important for a modern PSU. So, the selection of connectors and the length of cables are quite satisfactory for a PSU of such wattage.
There’s nothing extraordinary about the specs. Having a higher wattage rating than the HCG-620M, the EA-650 Platinum offers the same load capacity of the +12V rail and is even inferior in the load capacity of the +3.3V and +5V rails. Well, 105 watts is quite enough for almost any modern system anyway. We can remind you that our rather advanced reference PC configurations marked in the cross-load diagrams consume a mere 40 watts from the +3.3V and +5V rails.
The more surprising feature of this PSU is that its +12V rail is split up into four virtual lines, each of which has a load capacity of 30 amperes. Why so many lines if two would be quite enough for the combined 48 amperes? And it would even be simpler to do without any splitting of the +12V rail, just like in the HCG-620M model.
It’s interesting to compare the EA-650 Platinum specs with the FSP Aurum model of the same wattage rating. The Antec permits lower loads on each of the main power rails. This limitation must have been necessary to meet the strict efficiency requirements of the 80 PLUS Platinum standard.
Working together with our APC SmartUPS SC 620, this PSU was stable at loads up to 385 watts when powered by the mains but could only switch to the UPS’s batteries at loads up to 295 watts.
When the computer is idle, the +12V voltage may be 3% off the required level, but this deflection lowers to 1-2% at higher loads. This voltage can deflect by more than 3% only in the unrealistic scenario when there's high load on the +3.3V and +5V rails and low load on the +12V rail.
The +5V voltage is always within 3%. And it only gets more than 2% off the required level when there’s a very low load on the +3.3V and +5V rails.
The +3.3V rail keeps its voltage within 3% of the required level in the typical load range, too. In fact, this voltage is within 2% at most load combinations.
Summing it up, the EA-650 Platinum delivers very stable voltages for a PSU without dedicated voltage regulation. Many PSUs that have the latter can't boast such stability.
The high-frequency voltage ripple at full load is conspicuous but meets the requirements of the industry standard.
The same goes for the low-frequency ripple.
The EA-650 Platinum is actually very close to the similarly designed FSP Aurum series in this test.
A poor fan regulation algorithm was our main concern about the FSP Aurum series which are very similar in design to this Antec EA-650 Platinum. So, the good news is that the Antec has more adequate fan regulation. However, it is still rather noisy.
It is cooled by a Yate Loon D12BH-12: a 7-blade 120mm fan with a rated speed of 2300 RPM.
The fan keeps on working at its initial speed until a load of 220 watts. Then it accelerates smoothly. The problem is that the initial speed is as high as 1050 RPM, so the fan can be heard even when the computer doesn’t work at high load. At full load the speed of the fan is over 1800 RPM. In fact, the fan gets annoying at loads of 300 watts and higher.
So again, the initial speed is too high. The fan won't be uncomfortable at 1070 RPM during the day, but most users would want something quieter for the night.
Perhaps replacing the fan with a D12BM-12 (1700 RPM) or even D12BL-12 (1200 RPM) would help since such fans are quite capable of coping with the high-efficiency PSU. As it is, the EA-650 Platinum is rather too noisy, even though not as noisy as the FSP Aurum series we tested earlier.
At the reference loads of 20%, 50% and 100% the EA-650 Platinum is 89.1%, 92.7% and 89.8% efficient. Its peak efficiency, as measured in our test, was 92.9% at a load of 334 watts.
That’s an excellent result but we must note that the PSU stopped almost 1% short of the Platinum standard according to our numbers, even though we connect PSUs to 220V mains in which they are a little more efficient than in 115V mains used for the 80 PLUS certification.
This model is officially listed among 80 PLUS Platinum products with results of 90.52%, 92.03% and 89.01%, so this discrepancy must be due to some measurement inaccuracies of our testbed, especially at low loads. We just can’t afford the high-precision testing equipment used by the certification organizations.
By the way, our results match the official ones (considering the different mains) well enough at the medium and maximum loads.
The power factor of this PSU is over 99% at high loads, which is a very good result.
The standby source copes with its job without any problems.
Although extremely efficient and stable in terms of its output voltages, this PSU is not perfect. It even has a serious downside in the end-user’s eyes: it’s too noisy. Its fan regulation algorithm has improved compared to the FSP Aurum series we tested earlier but the speed of the fan seems to be too high at any load. It’s just unreasonable to make the fan work at 1000 RPM at low loads and 1800 RPM at high loads in such a highly efficient PSU that doesn’t get as hot as to require such intensive cooling.
This is the senior model in Chieftec’s entry-level A80 series which ranges from 350 to 600 watts.
The CTG-600-80P is shipped in a small box that turns out to be unexpectedly heavy for its size (and the product price, too). The box design is the same for every model in the series. You can only identify the specific model by the mark next to it in the list of model names.
The PSU comes with a mains cord, mounting screws and a user manual.
The manual covers two PSU series from Chieftec: A80 and A85.
The CTG-600-80P has an unremarkable appearance: an unpainted case with thin panels and a 120mm fan shifted slightly off the center. The exterior matches the price, actually. The lower-wattage HIPRO is the only PSU in this review to be cheaper.
There’s an On/Off switch on the honeycomb back panel.
There are four holes in the panel with cables but they are too small to be vents. The PSU lacks any other openings in its case.
Combined with its specs, the interior design of the CTG-600-80P helps easily identify its actual maker. It’s Sirfa.
There’s nothing extraordinary about the interior. The PSU lacks dedicated voltage regulation and is generally not as advanced in its circuit design as newer solutions, like the above-discussed Antec based on a FSP platform.
The CTG-600-80P features active power factor correction but is only designed for 230V mains.
The combined PWM and PFC controller is implemented as a FAN4800IN chip from Fairchild Semiconductor.
A PS224 chip is responsible for monitoring and protection.
The CTG-600-80P employs rather high-quality Teapo capacitors.
The CTG-600-80P is equipped with the following cables and connectors:
The mainboard cable is sleeved. Its solid connector doesn’t have a detachable 4-pin part for compatibility with old mainboards. That’s okay because modern products have been using 24-pin power connectors for many years already.
The free-flying pair of additional pins for the first graphics card connector looks odd. This connector may even seem to be of the 6-pin variety at first sight.
Overall, the selection of connectors is sufficient for a PSU of that wattage and the cables are long enough, except for the CPU cable with 8-pin connector which may turn out to be too short in some system cases with a bottom PSU bay. We guess a 4+4-pin connector on a 65 to 70-centimeter cable would be guaranteed to match any system case.
The CTG-600-80P cannot support a high load on the +12V rail: only 504 out of its full 600 watts. In fact, the PSU can hardly work at loads higher than 550 watts because it’s virtually impossible to find about 100 watts of load for the +3.3V and +5V rails in a modern PC.
The rest of the specs are quite conventional. The combined load capacity of the +3.3V and +5V rails is 150 watts. The standby source can deliver 2.5 amperes.
The CTG-600-80P lacks any official 80 PLUS certification although we can see a badge on its label stylized to look like that certificate. In fact, the self-made badge has the same meaning because the manufacturer promises the PSU to be over 80% efficient in 230V mains.
Connected to our APC SmartUPS SC 620, the PSU was stable at loads up to 375 watts when powered by the mains but couldn’t switch to the UPS’s batteries even at 280 watts.
The +12V rail is just as stable as in many other PSUs without dedicated voltage regulation. This voltage deflects the most from the required level when there’s moderate load on the +12V rail and high load on the other rails.
The +12V voltage is not going to be more than 4% off in the typical load range, though.
The +5V voltage is very stable, being only 3% off when there’s very high load on the +5V and +3.3V rails.
The +3.3V rail is similar to the +12V one. Its voltage can be up to 4% off the required level at low loads.
The CTG-600-80P was unstable at zero load on the +5V rail (we had to set this voltage higher to avoid triggering the PSU’s protection) but the real picture of low loads this PSU can support is better than in our diagram. The fact is the PSU would lose the Power OK signal when the load was suddenly switched to the +12V rail as is typical of this test, although the voltages were all within the permissible limits. By increasing the minimum load on each rail we made the PSU stable for our test, but such sudden changes in load can hardly occur in real-life usage scenarios.
The high-frequency voltage ripple is quite strong, the occasional spikes on the +12V rail even going beyond the permissible limits.
The same goes for the low-frequency ripple. It is within the required limits except for occasional spikes on the +12V rail.
The PSU is cooled by a 7-blade 120mm Globe Fan S1202512L running on a sleeve bearing. This fan should be given credit for being the quietest among all in this review. It lacked any foreign noises that could be heard from the other fans from a close distance. However, the sleeve bearing is going to have a shorter service life than the ball bearings of the other PSUs’ fans.
The fan speed is no higher than 800 RPM until a load of 200 watts. The PSU remains noiseless at 1000 RPM and 250 watts thanks to the wire grid and high-quality fan. It is only at loads of 400 watts that the noise becomes annoying. The fan just can’t help producing a hiss of air flow at speeds above 1300 RPM.
The fan accelerates to 1700 RPM by the load of 500 watts and maintains that speed until full load.
The regulation algorithm is quite adequate but the fan might work at a lower speed considering the low temperature of the PSU at load.
Thus, the CTG-600-80P is almost silent at medium loads but becomes noisy at high ones.
At the reference loads of 20%, 50% and 100%, the CTG-600-80P was 86.1%, 87.1% and 83.2% efficient. Its peak efficiency of 87.6% was observed at 313 watts. That’s a very good result for a PSU that lacks any kind of official 80 PLUS certification.
The power factor is 98% at most loads, which is quite good, too.
There are no problems with the PSU’s standby source.
The Chieftec CTG-600-80P is an inexpensive product with good electrical properties. It is noisy at high loads and somewhat unstable at zero or suddenly changing loads.
The previous 600W model was the highest-wattage PSU in the A80 series but the SPS-650C with its wattage rating of 650 watts is the junior model in the Nitro 88+ series which goes all the way up to 1000 watts.
The product’s box is larger in every dimension than the packaging of its entry-level cousin and has a carry handle. We can spot an 80 PLUS Silver certification badge on the front of the box.
The PSU and mains cord are packed into individual velvet pouches. There is no pouch for unused detachable cables, though. Like with the above-discussed A80 series model, the user manual covers two PSU series from Chieftec: Nitro 85+ and Nitro 88+.
Although there’s nothing special about this PSU’s design, its coloring is surely eye-catching. The panels of the case are rather thick. The cover of the case is secured with more screws than usual.
We can see four vent slits in one of the side panels. There’s an On/Off switch on the back panel.
The interior design of this product helps us name its actual maker as Channel Well, although there are some differences from Channel Well platforms we’ve tested.
Comparing this interior to that of the Chieftec BPS-650C (the CWT PSH II platform), we can see they are similar in their component layout, yet also differ in many respects.
The dedicated voltage regulation is now based on DC-DC converters instead of magnetic amplifiers. Some of output electrolytic capacitors have been replaced with solid-state ones. A choke has been added into the filtering circuitry while the heatsinks have become more complex.
All of this must have been meant to make the PSU more efficient to meet the 80 PLUS Silver requirements because the BPS-650C model was only Bronze-certified.
As for controller chips, the PS229 supervisor is the same as in the BPS-650C. The PWM & PFC controller is now represented by a CM6802TAHX chip instead of a CM6800G.
There are electrolytic capacitors from United Chemi-Con at the PSU’s output. They enjoy an excellent reputation.
The Chieftec SPS-650C is equipped with the following cables and connectors:
Included with the PSU are:
The cables are almost the same as those of the BPS-650C model (with the addition of a second CPU cable) but somewhat longer. So, we can again complain that there are only two graphics card cables included into the box although the PSU has four connectors for them. The Chieftec SPS-650C is quite capable of powering up a couple of performance-mainstream graphics cards with two power connectors each linked in a SLI or CrossFireX configuration, but you’ll have to use adapters for it due to the lack of cables.
The Chieftec SPS-650C differs from the BPS-650 model we tested earlier in the load capacity of the +12V rail which is 12 watts lower. Overall, the specifications are up to today’s standards.
The PSU itself and its box bear the 80 PLUS Silver badge but are not listed among officially certified products. Moreover, there are no Chieftec PSUs at all with Silver certification.
The Chieftec SPS-650C has been selling for over a year already, so this can hardly be due to the official 80 PLUS website being slow to update. It is also doubtful that Chieftec would use the certification badge without any reason (Chieftec does put self-made certificate badges on its products from time to time but they do not copy the official 80 PLUS badge).
Working together with our APC SmartUPS SC 620, this PSU was stable at loads up to 388 watts when powered by the mains. They could switch to the UPS’s batteries at loads up to 330 watts.
The +12V rail is rock-solid, its voltage never being more than 1% off the required level!
The +5V voltage is just as stable. It is not going to be more than 2% off in the typical load range.
The +3.3V voltage can only get 3% off the required level when the load on the +12V rail is close to the maximum. Overall, the Chieftec SPS-650C must be praised for delivering extremely stable voltages.
The high-voltage ripple is noticeable on each rail but is always within the permissible range.
It’s even better at the double frequency of the mains: the ripple is weaker on the +12V rail and much weaker on the +3.3V and +5V rails.
The Chieftec SPS-650C is cooled by a 7-blade Yate Loon fan (D14SM-12, 140 mm, 1400 RPM). Like the fan of the Chieftec CTG-600-80P, it runs on a sleeve bearing but can’t match the latter’s noiselessness. Well, this fan is quiet, too. You can hear some unwanted sounds only if you put your ear right next to the PSU case.
The fan regulation algorithm is just perfect. The fan works at a noiseless 800 RPM until a load of 550 watts. Then it accelerates suddenly, yet only to 1200 RPM.
Take note that the difference in temperature between the incoming and outgoing air remains the same after the fan starts to accelerate. This seems to be perfect regulation: the fan is comfortable at most loads yet protects the PSU from overheat.
So, the Chieftec SPS-650C is one of the quietest in its class. It is virtually silent at most loads and is quieter than most of its competitors at full load.
The PSU was 88.6%, 89.9% and 88% efficient at the reference loads of 20%, 50% and 100%, respectively. Its peak efficiency of 90.3% was observed at loads of 378 to 402 watts.
These results almost match the 80 PLUS Gold requirements and meet the Silver certification by a large margin.
The power factor is about 99%, which is a good result, too.
The standby source copes well, but its voltage is 4% off the required level at full load.
The Chieftec SPS-650C is very quiet at any load and boasts exemplary stability of voltages, high efficiency and reasonable pricing. Our minor complaints about secondary electrical parameters (which all meet the requirements of the industry standard, though) and cables have no chance to blemish the numerous advantages this model has to offer.
We’ve never tested products from HIPRO before, but this is actually the PSU brand of Chicony, which is a much better known name. Chicony claims that all of its products are manufactured on its own facilities.
The HIPRO HP-D5201AW comes from the entry-level K1 series which even lacks basic 80 PLUS certification. The series ranges from 460 to 630 watts. Although not particularly new, it is still widely available in shops.
The HIPRO HP-D5201AW is shipped in a medium-sized glossy cardboard box. The design is gaudy with multicolored lines of text against a blue background and a picture of a submarine (we really wonder what relation might exist between this ATX power supply and the U-Boot-Klasse XXI).
The packaging is unified for not one but two PSU series: K1 (our model comes from it) and K2 (it has a somewhat shorter range of wattage ratings and features basic 80 PLUS certification).
Besides the PSU, the box only contains a mains cord.
The HP-D5201AW seems to have a regular design with a 120mm fan behind a wire grid, thick panels of the case and black paint.
Besides an On/Off switch, there is a LED indicator on the back panel that shows you if the PSU is turned on.
The unusual thing about this PSU design is that the detachable part of the case includes the front, top and bottom panels instead of top and side ones, as usual.
The unusual design of the case allows us to have a look at the reverse side of the main PCB.
We can note quite a number of neatly soldered small components here.
The HP-D5201AW is a typical inexpensive PSU with active PFC and no dedicated voltage regulation.
The PWM & PFC controller and the supervisor chip reside on a daughter card near the front panel of the case.
A popular CM6800G chip is responsible for PWM and PFC.
A less popular CP006WD chip is responsible for monitoring and protection.
Judging by the PCB marking, HIPRO K1 and K2 series products all share the same PCB. We can also note the unusually small size of the SamXon capacitors at the input:
The PSU employs electrolytic capacitors from Ltec at the output. They are not considered high-quality components.
The HIPRO HP-D5201AW is equipped with the following cables and connectors:
Every cable is sleeved up to the first connector. Although the cables aren’t very long, the CPU one should be long enough for system cases with a bottom PSU bay.
The PSU only offers four SATA power connectors on two cables. That’s too few for today’s PC configurations.
The HP-D5201AW specs are typical of entry-level PSUs. The load capacity of the +12V rail is only about 80% of the PSU’s total output power. The latter is but slightly lower than the combined load capacities of all of the power rails.
The PSU comes from the K1 series and lacks any official 80 PLUS certification which is only available with the K2 series.
Working together with our APC SmartUPS SC 620, the PSU was stable at loads up to 372 watts when powered by the mains but couldn’t switch to the UPS’s batteries even at 280 watts.
The HP-D5201AW is rather poor in this test even for its class:
The +12V diagram is typical of PSUs without dedicated voltage regulation. However, there is an additional problem here: the +12V voltage sags too much when there’s a high load on the +12V and a low load (less than 10 watts) on the other rails.
The +5V voltage is more than 5% off the required level at loads above 100 watts, so it doesn’t meet the PSU specs. On the other hand, this voltage is going to be within 3% in the typical load range.
The +3.3V rail is the most stable one. Its voltage is always within 3% of the required level and even within 2% in the typical load range.
The high-frequency voltage ripple would be normal if it were not for the huge spikes that coincide with the transistors’ switching.
The same goes for the low-frequency ripple.
We don’t think this is going to affect the functioning of the PSU, yet we wouldn’t recommend it to audiophiles.
The PSU is cooled by a 7-blade 120mm Superred CHB12012DS fan manufactured by the Taiwanese firm Cheng Home Electronic.
Alas, the HP-D5201AW is far from quiet. The initial speed of its fan is as high as 1200 RPM, which is quite audible already. The fan begins to smoothly accelerate at loads of 200 watts and higher, reaching 2500 RPM at full load. And that’s not just loud, but very loud. For all this noise, we can’t say the PSU is cooled well. The difference between the incoming and outgoing air is up to 11°C, which isn’t small.
Thus, this PSU can’t be recommended to anyone who cares about noise.
The HP-D5201AW is 85.5%, 86.6% and 82.7% efficient at 20%, 50% and 100% load, respectively. Its peak efficiency of 86.8% was observed at a load of 265 watts.
The efficiency meets the 80 PLUS Bronze requirements although this PSU series lacks even basic 80 PLUS certification.
The power factor is rather low for a PSU with active power factor correction. It’s not higher than 96.2% although active PFC is expected make it as high as 98-99%.
The standby voltage doesn’t sag at high loads.
The HIPRO HP-D5201AW features unexpectedly high efficiency and good exterior design (high-quality metal, sleeved cables) but it is very noisy and doesn’t deliver stable voltages.
OCZ’s Mainstream Performance PSUs include this ZS series and the CoreXStream Series 500W. The OCZ-ZS550W is the junior model in the ZS series which comes in wattages of 550, 650 and 750 watts.
The PSU is shipped in a medium-sized black-and-blue box which is individual for each model in the series.
The box seems to lack a carry handle, but you can spot a cutout in the cardboard when you turn the box upside down.
Here’s the handle.
The accessories include a user manual, fasteners and a mains cord.
The OCZ-ZS550W is painted the same black and blue as its box. There’s nothing extraordinary about its appearance except that the fan grid lacks a manufacturer logo in the center.
The rim of the fan cutout is somewhat sunken in to reduce the gap between the PSU case and the fan impeller. This should have a positive effect on the fan’s noisiness.
The back panel is a honeycomb mesh. The mains connector and On/Off switch are complemented with a sticker informing you that this PSU is designed for 230V mains only.
The previous OCZ product we tested – the ZX1000W model – was manufactured by the Chinese maker Great Wall. The OCZ-ZS550W comes from the better-known Sirfa.
Although from a junior product series, the PSU features a rather advanced design. Particularly, it boasts dedicated voltage regulation based on magnetic amplifiers.
It also has active PFC but is limited to 230V mains.
The quality of assembly and soldering is high.
The CM6800TX chip serves as a PWM & PFC controller.
The 4-channel supervisor Sitronix ST9S423 is responsible for monitoring and protection.
The PSU employs high-quality United Chemi-Con capacitors at its output.
The OCZ-ZS550W is equipped with the following cables and connectors:
Every cable is sleeved. All of the cables are long, except for one with SATA connectors, so this PSU is going to be suitable even for very large system cases. However, these long cables may become a problem in a compact case where you have to hide them somewhere.
We can also note that the connectors are placed too close to each other on each cable, which may be a problem, too. We guess it’s easier to connect, for example, hard disks if the connectors are placed with a gap of 15 rather than 10 centimeters on a PSU cable.
The selection of connectors is quite sufficient for the PSU’s wattage.
There is only one indication that this PSU is not very advanced. The load capacity of its +12V rail is only 456 watts or just a little higher than 80% of the full output power.
The rest of its specs are normal: up to 130 watts on the +3.3V and +5V rails combined and up to 3 amperes on the standby source.
The OCZ-ZS550W has 80 PLUS Bronze certification.
Working with our APC SmartUPS SC 620, this PSU was stable at loads up to 375 watts when powered by the mains but couldn’t switch to the batteries even at 280 watts.
The +12V and +5V voltages are within 3% of the required levels. These power rails are especially stable at high loads.
The +3V voltage is also closer to the required level at high loads, but its maximum deflection is 4%.
As opposed to most PSUs in this review, the OCZ-ZS550W isn’t very stable at very low loads but its overall performance in this test is good.
The high-frequency voltage ripple isn’t strong, yet there are voltage spikes above the permissible limits.
The same goes for the low-frequency ripple.
The PSU is cooled by a 135mm Globe Fan RL4Z B1352512M fan. It won’t be easy to find a replacement if the default fan fails. On the other hand, fans with ball bearings usually have a very long service life. The fan has 11 blades and a rated speed of 1200 RPM. It is partially covered with a piece of plastic to optimize air flows.
Together with the Chieftec SPS-650C, the OCZ-ZS550W is the best in this review in terms of acoustic comfort. It is even quieter at low loads, its fan rotating at 650 RPM or less. This speed is maintained until a load of 230 watts.
Then the fan accelerates smoothly, reaching 1000 RPM at 430 watts and 1125 RPM at full load.
The PSU is silent at low and medium loads and quite comfortable at high loads.
At the reference loads of 20%, 50% and 100% this PSU was 83.9%, 86.1% and 83% efficient. The peak efficiency of 86.3% was spotted at 240 watts. Thus, the OCZ-ZS550W confirms its Bronze status.
The power factor couldn’t reach 98% at high loads, unlike in most other PSUs with active power factor correction.
We can see no problems about the standby source.
The OCZ-ZS550W has good electrical parameters and comes at an attractive price. It is virtually silent at medium loads. Its long cables make it suitable for large system cases.
The Chieftec Nitro 88+ SPS-650C and the OCZ OCZ-ZS550W are the best products in this review. Both are quiet and affordable. The OCZ is just a little more expensive than the noisier and less advanced Chieftec CTG-600-80P and HIPRO whereas the Chieftec SPS-650C, being cheaper than the Antec HCG-620M, is superior to the latter in efficiency and noiselessness. Therefore, we are proud to award these two PSUs with our Recommended Buy title:
This pair of leaders has overshadowed the Chieftec A80 CTG-600-80P and Antec High Current Gamer HCG-620M which are quite good for their class, too. You may want to consider them if the better models are not available. Our main gripe about them is that they are rather noisy at high loads, although quiet at medium ones.
Antec’s EarthWatts EA-650 Platinum is let down by its fan regulation algorithm. As a result, this Platinum-certified model may only be interesting for eco-conscious users who are willing to save a few watts of power at the expense of their acoustic comfort. If you dare risk your warranty and replace the default fan with a slower one, this PSU might be far more interesting. There are no Platinum-certified PSUs in the same price category and it has no other problems save for the noisiness.
And finally, the HIPRO HP-D5201AW can hardly be recommended at all. It is the loudest at any load, has some problems with electrical parameters and is but slightly less expensive than the higher-wattage and overall better products from OCZ and Chieftec.