by Dmitry Vasiliev
11/12/2012 | 01:32 PM
PSUs with ratings of 600 to 700 watts enjoy higher demand than their higher-wattage counterparts we discussed in our previous review. They can easily power a rather advanced PC configuration with one top-end graphics card or a couple of mainstream GPUs, even if overclocked. There’re a lot of gaming computers like that because few people are ready to shell out for two top-end graphics cards at once. And today we are going to have a look at an affordable Chieftec, a series of three PSUs from Cooler Master, Corsair models from three different series, and one Zalman.
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.
This PSU is most affordable for a semi-modular model with a wattage rating of 650 watts.
The Chieftec CTG-650C is shipped in a medium-sized box which is designed in a uniform way for all three models in the series. The specific model is indicated with a red checkmark in the list on the box. The CTG-650C is a midrange model since the series also includes 550W and 750W products.
There are no extra accessories in the box. You only get a user manual (traditionally for Chieftec, it refers to two different PSU series, A80 and A85), a mains cord, screws and modular cables.
The CTG-650C looks simpler than Chieftec’s more expensive PSU series. Its painted surface isn’t excessively rough, the metal of its case is thinner and its fan is only 120 mm in diameter.
The specifications table we’ve seen on the side panel is duplicated on the PSU’s bottom. The back panel is a honeycomb mesh. An On/Off switch can be seen next to the mains connector.
The Chieftec CTG-650C features high component density inside. Its design peculiarities and specified electrical parameters suggest that its actual maker is Sirfa. We mean the High Power Performance Pro series with some modifications: no support for the full input voltage range, a smaller fan, no fan connectors, and modular design. Together with CWT, Sirfa is the main contract manufacturer for Chieftec.
The three chokes in the output circuitry area indicate dedicated voltage regulation based on magnetic amplifiers. Thus, the Chieftec CTG-650C is functionally close to the more expensive Chieftec BPS-650C: semi-modular design, dedicated voltage regulation, active PFC and the same output power.
The CM6800TX chip located on a daughter card next to the large input capacitor serves as a PFC & PWM controller.
The PS223 supervisor chip is responsible for monitoring and protection.
The Chieftec CTG-650C employs high-quality Teapo capacitors at the output.
The Chieftec CTG-650C is equipped with the following cables and connectors:
Included with the PSU are:
The cable system is okay for a PSU of that class, yet we can note a few shortcomings. The CPU power cable is rather too short (counting to the 8-pin connector). You won’t be able to power two graphics cards with two 6-pin power connectors each without adapters (but, considering the rather low load capacity of the +12V rail, the PSU doesn’t seem optimal for such dual-GPU configurations anyway). And since one SATA power cable goes to the optical drive, you only have the other cable with three SATA connectors for your HDDs and SSDs.
Although similar in functionality to the more expensive Chieftec BPS-650C, the Chieftec CTG-650C can’t match the latter’s electrical specs. The load capacity of the +12V rail is almost 100 watts lower than the PSU’s full output power, and it can only work on 230V mains notwithstanding its active power factor correction.
The Chieftec CTG-650C lacks 80 PLUS certification because consumer-class PSUs are only certified for 115V mains, but the manufacturer claims that its peak efficiency is over 85%.
Working together with our APC SmartUPS SC 620, the PSU was stable at loads up to 382 watts when powered by the mains but could only switch to the UPS’s batteries at a load of 280 watts.
The main +12V voltage is far from stable, barely staying within the permissible range at low loads. Moreover, the PSU was unstable at zero loads on the +12V rail (which is hardly possible in a real-life computer, though). You can also note that the +12V voltage gets better as the computer consumes more from the +12V rail, being within 1% of the required level at near-maximum loads.
The two other voltages remain within 3% of the required levels (the +3.3V voltage goes out of this range at minimum loads only). That’s a good result considering the price of the PSU. Its overall performance in this test is quite satisfactory.
The high-frequency voltage ripple isn’t strong, yet there are spikes on each power rail which may go out of the permissible range.
The same goes for the low-frequency voltage ripple except that there are fewer voltage spikes here.
The PSU is cooled by a 120mm 7-blade Globe Fan S1202512L which has a rated speed of 2000 RPM and runs on a sleeve bearing.
The fan starts out at below 800 RPM and maintains that speed until a load of 230 watts. Then it accelerates linearly, reaching 1700 RPM at full load. The fan is audible at 1000 RPM and 330 watts and becomes downright uncomfortable at 1300 RPM and higher (or at loads of 500 watts).
Overall, the Chieftec CTG-650C is average in noisiness at high loads and quiet at medium loads.
The Chieftec CTG-650C is 84.3%, 87.2% and 83.3% efficient at the reference loads of 20%, 50% and 100%, respectively. It shows its peak efficiency at 50% load, thus delivering on the manufacturer’s promise of 85+. Overall, its efficiency is similar to many PSU models we’ve seen which have 80 PLUS Bronze certification.
The power factor is about 98% at full load, which is typical of PSUs with active power factor correction.
There are no problems with the standby source.
The Chieftec CTG-650C offers good electrical parameters and semi-modular design at a very affordable price. Its +12V voltage might be more stable and it might have weaker output voltage ripple, yet there are quite a lot of much more expensive PSUs that have the same downsides.
These three PSUs from Cooler Master all hail from the recently released GX-Lite series which is meant to be functional, yet also affordable.
The 500W model doesn’t fit into the wattage range designated in the Introduction, but it just goes together with its senior cousins.
The PSUs are shipped in small boxes with individual design.
The overall design style is uniform, yet each model has an individual color.
There’s a bare minimum of accessories inside: a user manual, a mains cord, and some mounting screws.
The PSUs look simpler even than the RS-400-PSAP model from the Elite Power series which we criticized for overstating its real specs and offering a limited selection of connectors. The fan has a punched-out grid. The cables are not sleeved. The thin steel of the case is unpainted.
It’s quite a surprise to see an On/Off switch on the back panel, considering such harsh cost-cutting measures.
The interior design of the two lower-wattage models is almost identical (the 500W and 600W models are shown in the top and bottom photos, respectively):
These are typical entry-level solutions without dedicated voltage regulation.
The single feature these PSUs can sport in terms of circuit design is active power factor correction.
The 500W and 600W models employ a CM6805BSX chip as a PWM & PFC controller. The chip can be found between the input capacitor and the front panel of the case.
Overall, the design looks outdated and primitive compared to the other PSUs in this review.
The senior model is more interesting, though.
It is obviously based on a different platform. The PCB wiring and the component layout differ.
A third choke is added in the output circuitry area, which means that this PSU, just like the Chieftec CTG-650C, supports dedicated voltage regulation based on magnetic amplifiers. Its output power is higher than the Chieftec’s (by almost 20% on the main +12V rail, which is a considerable difference) whereas its price is a little bit lower.
It is rather odd that the dedicated voltage regulation is not advertized on the manufacturer’s website while the interior design is only illustrated with photos of the junior models.
Each of the three Cooler Master PSUs features Teapo capacitors which are rated for an operating temperature up to 105°C (at the output) and 85°C (at the input).
The actual maker of each PSU is ATNG, a brand we’ve never encountered before. Judging by the specs, Cooler Master’s products are additionally improved compared to their basic versions from ATNG.
The RS-500-ASAB and the RS-600-ASAB are equipped with the following cables and connectors:
The RS-700-ASAB model additionally has one more graphics card cable with two 6+2-pin connectors and one more CPU cable with a 4+4-pin connector.
The selection of cables and connectors is quite sufficient. However, the cables are very thin (20AWG compared to the standard 16AWG section) and are not sleeved. The connectors of the CPU and mainboard power cables are not easy to deal with because their parts do not hold tight together.
The specifications improve as we move up the series. The junior model can only deliver 423 out of its full 500 watts via the +12V rail whereas the midrange model’s 540 out of 600 watts is much better both in absolute (there’s 60 rather than 68 watts left for the less used power rails) and relative (the +12V rail can deliver 90% rather than 86.4% of the PSU’s full output power) numbers. The senior model offers the best specs, of course. It can yield 660 out of its full 700 watts via the +12V rail and its efficiency is 88% as opposed to the other models’ 86%.
Like the above-discussed Chieftec, the Cooler Master PSUs are only designed for 230V mains.
Working together with our APC SmartUPS SC 620, the RS-500-ASAB was stable at loads up to 354 watts when powered by the mains. Its 600W and 700W cousins were stable at up to 362 and 392 watts, respectively. None of them could switch to the UPS’s batteries even at a load of 290 watts, though.
We’ll build our diagrams for each PSU individually for better readability.
This model performs expectedly for a PSU without dedicated voltage regulation. Its +12V voltage goes out of the permissible range when there’s a moderate load on the +12V rail and a high load on the other rails. The +5V voltage is unstable at loads above 80 watts while the individually regulated +3.3V voltage is the most stable of all.
We must note, however, that the voltages are close to the required levels in the typical load range.
The 600W model performs in the same way except that the +5V voltage goes out of the permissible range at higher loads, and the +12V voltage does the same only when the overall load is misbalanced towards the other rails.
The flagship model of the series does much better thanks to its dedicated voltage regulation.
The +12V voltage is just perfect, remaining within 1% of the required level at any load. The +5V voltage is always within 3%, which is good, too. The +3.3V voltage is the least stable of all, going beyond 3% at very low loads. Overall, the RS-700-ASAB delivers very stable voltages.
We must note, however, that each of the Cooler Master PSUs doesn’t work well at minimum loads. When not loaded at all, the +5V rail would trigger protection in the two junior models. And when we lowered the load on the +12V rail from the maximum to the minimum during our test, each model would lose the Power OK signal. We saw the Chieftec CTG-600-80P PSU behave like that, although it was based on a different platform.
We’ll show you the results of the models based on different hardware platforms.
The high-frequency voltage ripple of the 600W model is conspicuous on each power rail but is always within the permissible range.
The low-frequency ripple is much weaker.
The 500W model behaved in the same manner as its 600W cousin but its output voltage ripple was weaker overall.
The 700W Cooler Master features a different platform and has stronger voltage ripple on the +5V rail. However, it lacks any voltage spikes on the +12V rail which could be observed with the two junior models.
The low-frequency voltage ripple is weak and can barely be observed on the +12V rail only.
Each of the three Cooler Master PSUs is cooled by a 120mm Globe Fan S1202512L (it’s the same fan as in the above-discussed Chieftec). The only difference is that the impeller is partially covered with a piece of plastic to optimize air flows in the 500W and 600W models. The 700W model has no such feature.
The fan regulation algorithm is the same for each PSU. The fan starts out at a very low speed and maintains it for a long time. Then the fan accelerates steadily until full load.
The 600W model is somewhat worse than its cousins. The start and maximum speed of its fan is somewhat higher and the fan begins to accelerate at a lower load.
The 700W model accelerates its fan later than its cousins. At full load it is in between the 500W and 600W models in terms of noisiness.
Thus, the 500W and 700W Cooler Master PSUs are rather quiet for their wattage. The 600W model is noisier, probably due to the variation in fan specs, which amounts to +/-10% for the Globe Fan S1202512L.
The Cooler Master RS-500-ASAB is 84.6%, 87.3% and 82.6% efficient at the reference loads of 20%, 50% and 100%. The peak efficiency of 87.6% was observed at a load of 260 watts.
The Cooler Master RS-600-ASAB is 86%, 86.3% and 82.4% efficient at the reference loads of 20%, 50% and 100%. The peak efficiency of 87.6% (the same as the junior model’s) was observed at a load of 240 watts.
The Cooler Master RS-700-ASAB is 86.8%, 88.2% and 86.5% efficient at the reference loads of 20%, 50% and 100%. The peak efficiency of 89.1% was observed at a load of 398 watts.
As you can see, the PSUs deliver on the manufacturer’s promise of 86% efficiency for the two junior models and 88% efficiency for the senior model.
The power factor is above 98% with the two junior models, which is normal for PSUs with active PFC. The 700W model is somewhat worse at 97%.
The Cooler Master PSUs are similar in terms of their standby voltage, so we’ll only show you the graph of the junior model:
Of course, the standby source does its job without any problems.
Cooler Master’s GX-Lite series PSUs are actually quite different among themselves.
The two lower-wattage models are mediocre solutions without special advantages or obvious downsides. Their price is low but they have a lot of competitors in their price range.
The 700W model is more interesting thanks to its dedicated voltage regulation and higher efficiency. It is the cheapest PSU we know of that has dedicated voltage regulation while the rest of its electrical and acoustic parameters are very good, too. Thus, the Cooler Master RS-700-ASAB is quite an attractive option as a high-efficiency PSU for little money.
This PSU comes from Corsair’s affordable Builder series. As its name suggests, the series is meant for computer integrators in the first place.
The plain packaging made of unpainted cardboard is not designed to attract a shopper’s eye.
It contains Corsair’s standard accessories set, though. Besides documentation, a mains cord and screws, the accessories include single-use cable straps.
The CMPSU-600CX V2 looks neat and nice, even though without any extravaganza.
The nonstandard cover design can be noted. When you remove the cover, the PSU is only left with one side panel. There are a mains connector and an On/Off switch on the back panel.
It’s easy to identify Channel Well’s DSAII platform with common voltage regulation.
The three massive heatsinks and the basic 80 PLUS certification imply that this model is no record-breaker in terms of efficiency.
There’s a Sitronix ST9S429 chip near the mains connector. It’s responsible for monitoring and protection.
The PWM/PFC controller is located on a small daughter card squeezed in between the A-PFC choke and the heatsink. The photo doesn’t permit to read its marking but we can tell you it’s a good old CM6800.
The PSU has electrolytic SAMXON capacitors at the output.
The Corsair CMPSU-600CX V2 is equipped with the following cables and connectors:
In fact, the selection of connectors is quite sufficient for PC configurations the PSU can power. The cables are long enough, too. The only problem you may encounter is that the spacing between the connectors on the SATA and PATA power cables is too small.
The specifications coincide with those of the original CWT DSAII 600W model and are not really up to today’s requirements. The PSU can only deliver 80% of its full output power via the most important +12V rail whereas the load capacity of the other rails is as high as 150 watts, which is hardly necessary for a modern PC.
The Corsair CMPSU-600CX V2 is certified to comply with the basic 80 PLUS standard.
Working together with our APC SmartUPS SC 620, the Corsair CMPSU-600CX V2 was stable at loads up to 362 watts when powered by the mains but couldn’t switch to the UPS’s batteries even at 280 watts.
The voltages are stable enough for a PSU without dedicated regulation. They only go out of the permissible range at greatly misbalanced loads, i.e. when there’s high load on the +3.3V and +5V rails and low load on the +12V rail or vice versa.
The high-frequency output voltage ripple isn’t weak, yet doesn’t go out of the permissible range except for short spikes on the +3.3V and +5V rails.
We see the same picture at the double mains frequency.
The Corsair CMPSU-600CX V2 is cooled by a 7-blade 120mm Yate Loon D12SH-12 fan which runs on a sleeve bearing and has a rated speed of 2200 RPM.
The fan starts up at 950 RPM and maintains this speed until 50% load. Then it accelerates in a linear manner, reaching 2000 RPM at full load.
Thus, the Corsair CMPSU-600CX V2 is rather quiet at low and medium loads, but louder than most of its competitors at high loads.
The Corsair CMPSU-600CX V2 is 86.1%, 86.9% and 82.3% efficient at the reference loads of 20%, 50% and 100%, respectively. It sports its peak efficiency of 87.5% at a load of 274 watts.
Overall, this model meets the 80 PLUS Bronze requirements but without any reserve at full load.
The power factor is above 98% at most loads, peaking at over 99%, which is a good result for a PSU with active power factor correction.
The standby source works blamelessly.
The Corsair CMPSU-600CX V2 is not very efficient, not very quiet and not very cheap. Its full duplicate (in electrical parameters) from CWT is about 20% cheaper (the CWT version has a simpler exterior design but its 140mm fan promises better acoustic parameters). There are many other worthy competitors in the same price category.
We’ve recently tested the senior model of this series. The GS600 and GS700 feature the same platform but differ in minor ways, starting from the accessories.
The accessories to our sample are the same as those of the above-discussed CX600: documentation, mounting screws, single-use cable straps and a mains cord.
The packaging is individual for each PSU model but follows a uniform style.
These PSUs do not differ externally from their senior cousin we tested earlier except that the junior model has only one color of the fan’s highlighting, which is blue. The GS700, like the GS800, offers red and white highlighting as well. The highlighting can be turned off altogether on both PSUs.
The exterior design is familiar from this aspect as well. The back panel carries Power and Highlight On/Off switches.
The GS600 and GS700 are almost identical in their interior design (the top photo shows the 600W model and the bottom photo, the 700W model):
There are different capacitors at the input, though. The number of wires going to the fan is varies too because the PSUs differ in highlighting. The small heatsink near the filtering chokes is shaped differently. And the lower-wattage PSU has a smaller choke to regulate the +12V voltage.
There are no changes otherwise. Each PSU has active PFC and produces its +3.3V and +5V voltages via the DC-DC converters located on the dedicated card near the front panel of the case.
Like the rest of Corsair PSUs in this review (and the GS800 model, too), the GS600 and GS700 have SAMXON capacitors at the output.
The Corsair GS700 is equipped with the following cables and connectors:
The GS700 has the same cables and connectors as its 800W cousin we tested earlier except that the latter has four graphics card cables. The GS600 only differs from the GS700 in one thing: its SATA power cables have three rather than four connectors each.
The lack of a pair of graphics card cables makes it easier to lay the cables out compared to the 800W model, but one cable with PATA power connectors is very likely to remain unused.
On the other hand, you won’t be able to power up a SLI/CrossFireX configuration built out of two graphics cards with two power connectors each without adapters.
Unlike the above-discussed CX600, the GS series models can yield almost all of their total output power via the +12V rail. Like the senior model of the series, the 600W and 700W models comply with the 80 PLUS Bronze requirements.
Working with our APC SmartUPS SC 620, the GS700 and GS600 were stable at loads up to 385 and 366 watts, respectively, when powered by the mains but couldn’t switch to the UPS’s batteries even at 280 watts.
The lower-wattage models are better than their 800W cousin in this test, but not by much.
The 600W model keeps its voltages within 2% of the required level in the typical load range but the maximum deflection is anyway no larger than 3%.
The GS700 is even better, always keeping its voltages within 2% of the ideal level. So, both PSUs are exemplary in terms of voltage stability.
The GS700 is comparable to its 800W cousin in this test in terms of both high- and low-frequency output voltage ripple. The GS600 has weaker ripple, but the difference isn’t large, so we only show you the diagrams of the 700W model.
The GS600 and GS700 are cooled by the same fans. It is the 140mm Ong Hua HA1425H12B-Z model as is employed in the GS800. The wiring differs due to different highlighting.
As you may have guessed, the top photo shows the GS600’s fan and the bottom photo, the GS700’s fan.
The fan regulation algorithm is the same as in the GS800: the fan turns on for a while at loads above 150 watts but only works constantly at loads about 300 watts. It accelerates linearly right after that, reaching almost 2000 RPM at full load. This is somewhat lower than the top speed of the GS800’s fan, but high anyway. That’s why these PSUs are silent at low loads but very noisy at high ones.
The Corsair GS600 is 85.6%, 88.3% and 84.7% efficient at the reference loads of 20%, 50% and 100%, respectively, meeting the 80 PLUS Bronze requirements by some margin. It showed its peak efficiency of 89% at a load of 256 watts.
The Corsair GS700 is 86%, 88.8% and 86.2% efficient at the reference loads of 20%, 50% and 100%, respectively, thus meeting the 80 PLUS Silver requirements even. Its peak efficiency of 89.2% could be observed at a load of 239 watts.
The power factor was above 99% with both PSUs at full load. This is an excellent result.
The two PSUs were similar in this test. Their standby voltage was always within the norm.
The GS600 and GS700 are affordable PSUs with modern circuit design and high efficiency but very noisy at high loads.
The last Corsair PSU in this review belongs to the TX series which is targeted at gamers and computer enthusiasts.
The TX650’s product box is the same size as those of the GS series but painted black and yellow. The packaging is individual for each PSU model.
The box contains the same stuff as included with the other Corsair PSUs in this review.
The TX650 looks more conservative than the GS series. It lacks any highlighting or ornamental plastic inserts. It’s similar to the GS series in one way, though. The top panel is fastened with hex-head screws.
The back panel is standard with a mains connector, an On/Off switch and a plaque with the PSU’s name.
We can see the familiar CWT PUQ (B) platform inside. It is used in Chieftec’s Nitro II 85+ and Corsair’s GS.
So, the functionality includes active PFC and dedicated voltage regulation based on DC-DC converters.
The Dc-DC converter card still doesn’t look neat. It is not as sloppy as in the GS800, though.
The Corsair TX650 has SAMXON capacitors at its output.
The Corsair TX650 is equipped with the following cables and connectors:
The PSU is shipped with two 10cm adapters from a PATA power connector to a floppy-drive plug. The cables are identical to those of the Corsair GS700 except that the floppy-drive plugs are connected via the adapters.
The Corsair TX650 allows a higher load on the +3.3V and +5V rails than the other PSUs based on the same platform we’ve tested earlier: up to 30 rather than 25 amperes for each voltage. The rest of the specs are familiar. The PSU can yield almost all of its output power via the +12V rail. It is 80 PLUS Bronze certified.
Working together with our APC SmartUPS SC 620, the PSU was stable at loads up to 387 watts when powered by the mains but couldn’t switch to the UPS’s batteries even at 280 watts.
The +12V voltage is perfect, always staying within 1% of the required level.
The other two voltages are within 2%. The Corsair TX650 is exemplary in this test.
The output voltage ripple, both high- and low-frequency, is within the permissible range, just like with the other Corsair PSUs based on the same platform.
The TX650 employs a different fan than what we’ve seen in the GS series. It is a 140mm Yate Loon D14BH-12 model with a rated speed of 2800 RPM.
The regulation algorithm hasn’t changed. The fan is idle at low loads, then turns on for brief periods of time, and then accelerates linearly at loads of 300 watts and higher. The fan reaches 1500 RPM at full load, which is an obvious advantage compared to the GS series which make their fan work at 2000 RPM.
Thus, the Corsair TX650 is quiet at medium loads and average in noisiness at high loads.
The Corsair TX650 is 87.3%, 89.3% and 84.9% efficient at the reference loads of 20%, 50% and 100%, meeting the 80 PLUS Bronze requirements. It lacks efficiency at full load to comply with 80 PLUS Silver. The peak efficiency of 90% was observed at a load of 248 watts.
The standby source copes with its job.
The Corsair TX650 is a quieter alternative to Corsair’s GS series.
We’ll wind up this review by taking a look at a PSU from Zalman.
The ZM700-GT is shipped in a rather small cardboard box that lacks a carry handle.
The accessories include a user manual, a mains cord, mounting screws, and some single-use cable straps. In fact, the same stuff is included with Corsair’s PSUs discussed above.
There’s nothing special about the exterior of this PSU. Its case is made of rather thin metal. It is painted black and has a black wire fan grid.
The gloomy appearance is somewhat enlivened by the red and white of the labels and the embossed name of the manufacturer on one of the side panels.
The interior design looks very familiar.
Indeed, it is the good old FSP 80GLN platform we got to know over 6 years ago. FSP’s popular Epsilon series is based on it, too.
So, we’ve got a well-known circuit design with active PFC and no dedicated voltage regulation.
There’s a PS223 supervisor on a small daughter card.
There are different types of capacitors at the output, just like in currently produced FSP Epsilon PSUs. We can see a single Teapo and some other components from obscure brands.
The Zalman ZM700-GT is equipped with the following cables and connectors:
The Zalman ZM700-GT has almost the same cables as the 800W FSP Epsilon Pro 85PLUS 800 except that the four 6+2-pin connectors are placed on two cables and there is no CPU power cable with a 4-pin connector.
We can note that the FSP Epsilon Pro 85PLUS 700, which has the same wattage as the Zalman, offers fewer connectors for graphics cards and SATA devices.
A traditional problem with FSP-based products is that the CPU power cable isn’t long enough to be hidden behind the mainboard in a system case with a bottom PSU bay.
Besides, FSP’s native PSUs have color coding for the +12V cables referring to different “virtual” +12V rails. We had to find out which line went where by the hit-and-miss method.
The specifications are very close to those of the FSP Epsilon Pro 85PLUS 700 except that the Zalman can yield less than its full output power via the +12V rail while the load capacity of the other rails is somewhat higher.
Anyway, like the native FSP, the Zalman cannot deliver the whole specified output power via the three main rails. The specified 700 watts is arrived at by adding 24.6 watts from the standby source and the -12V voltage.
The Zalman ZM700-GT complies with the 80 PLUS Bronze requirements.
Working together with our APC SmartUPS SC 620, the PSU was stable at loads up to 359 watts when powered by the mains but couldn’t switch to the UPS’s batteries even at 280 watts, just like its FSP-branded cousins.
The Zalman ZM700-GT did better in this test than its FSP counterpart:
The +12V voltage is mostly within 3% of the required level except for very small areas of highly misbalanced loads.
The +5V and +3.3V voltages are also stable in the typical load range.
So, the Zalman ZM700-GT is quite good in this test for a PSU without dedicated voltage regulation.
The high-frequency voltage ripple is strong on the +3.3V and +5V rails but never exceeds the permissible limits. The native FSP products were better in this respect. The ripple is weaker on the +12V rail.
The low-frequency voltage ripple is weak on the +5V and +12V rails.
The fan is yet another different from the FSP Epsilon. Instead of a noisy Power Logic, the Zalman uses a Yate Loon D12SH-12 (120 mm, 2200 RPM). We’ve seen this fan in the Corsair CX600 already.
Alas, the quieter fan is let down by the poor regulation algorithm. The impeller accelerates right away, reaching over 1900 RPM at full load, which is 450 RPM higher than the fan speed of the FSP Epsilon Pro 85PLUS 700. The start speed of the Zalman’s fan is as high as 1000 RPM – the FSP only reached it at a load of 500 watts.
Thus, the Zalman ZM700-GT is anything but quiet.
The Zalman ZM700-GT is 85.2%, 87.5% and 84.7% efficient at the reference loads of 20%, 50% and 100%, which complies with the 80 PLUS Bronze specs. The peak efficiency of 88% was observed at a load of 371 watts.
The power factor is higher than 98%, which is typical of PSUs with active power factor correction.
The standby voltage is normal.
The Zalman ZM700-GT is a good alternative to the FSP Epsilon series in electrical parameters, but its fan regulation algorithm is inadequate.
If we were to choose from the PSUs covered in this roundup, we’d select the Corsair TX650. It offers stable voltages, doesn’t produce too much noise (as opposed to the Corsair GS series which is similar in all other aspects), has high efficiency and is reasonably priced. Therefore, we are proud to award Corsair TX650 our Recommended Buy title:
If your budget is limited, you may want to take a closer look at the Chieftec CTG-650C and the 700-watt Cooler Master GX-Lite. The Chieftec features semi-modular design and doesn’t look cheap. However, the Cooler Master costs less, offers higher efficiency and higher load capacity (especially for the +12V rail), and works quieter at medium and high loads.
Corsair’s GS series have unique exterior design and highlighting (one color with the GS600 model and three colors with the GS700). They are comparable to the TX650 model in electrical parameters (they are all based on the same hardware platform, after all) but inferior to the latter in acoustic comfort at medium and high loads. We guess this makes them less preferable for users who value quiet computers.
Cooler Master’s junior GX-Lite models, the Corsair CX600 V2 and the Zalman PSU turned out to be outsiders in our today's test session. These are the only PSUs in this roundup to have no dedicated voltage regulation.
The junior models of the Cooler Master GX-Lite series may only compete against other products in the same price range but not against the PSUs we’ve tested today.
The Corsair CX600 V2 is meant for PC integrators and seems to be overpriced. Its CWT-branded cousin is considerably less expensive. It has the lowest load capacity of the +12V rail among the 600W products in this roundup and is rather noisy at high loads.
Unfortunately, the Zalman ZM700-GT is let down by its inadequate fan regulation algorithm. Being among the most expensive PSUs in this roundup, it is exceedingly noisy.