by Dmitry Vasiliev
11/28/2011 | 09:37 AM
Generally speaking, there are but very few people who need power supply units with that much wattage. Even if you calculate the power requirements of an extremely top-end home computer (with two dual-GPU or three single-GPU graphics cards, a top-end CPU from AMD or Intel, half a dozen disks, etc), you will only come up with something like 800-850 watts.
Moreover, you won’t make such a computer consume that much power unless you launch heavy component-specific tests (Linpack, FurMark, IOMeter, etc) concurrently, which is hardly a normal usage scenario.
Thus, PSUs with a wattage rating of over 1 kilowatt may only be demanded by owners of monstrous gaming rigs who are also into overclocking. If you count yourself among them, read on!
Click the following link for a 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.
One additional note has to be given here: our testbed is limited to a load of 1100 watts on the +12V rail, so we could put the maximum specified +12V load on only one out of the four tested PSUs. We couldn’t test the other PSUs’ +12V rail at its max specified load.
The High Current Pro series unit from Antec is the most original among the four PSUs in this review, both externally and internally, but shares some common traits with the Antec Signature SG-850.
This PSU is somewhat larger than standard, having a length of 180 millimeters. The color of the case is unusual, too. Antec preferred to paint it dark-blue instead of the conventional black and gray hues.
Unexpectedly for such a high-wattage PSU, the cooling system consists of but a single 80mm fan. It is located at the back panel and covered with a punched-out grid. A mains connector and an On/Off switch can be found nearby.
Where not occupied by the connectors, the front panel of the case is a vent grid. There is even a small vent grid above the bunch of fixed cables.
There is a plaque with the manufacturer’s name on the top panel and stickers on the sides (with manufacturer’s name, product series and model name) and bottom (with product specifications) of the case.
The HCP-1200 has an unusual interior design. Its components reside on two PCBs fastened to the bottom and top panels of the case, which explains why the PSU is equipped with only one small fan. A larger fan just wouldn’t fit it.
Most of the components are mounted on the main PCB at the bottom of the case.
The HCP-1200 features dedicated voltage regulation based on DC-DC converters.
The pair of MOSFETs that are responsible for the +3.3V and +5V voltages are equipped with individual heatsinks and can be found in between the transformer and the upright daughter card. Smoothing chokes and solid-state capacitors of the converters can be seen on the main PCB nearby.
The top PCB, on its part, carries most of the input components that help convert the AC current from the mains.
The quality of soldering and assembly is blameless. The UL certificate number on the PCBs points at Dongguan Wannienfu Electronic Co., Ltd as the real manufacturer. It is a contract maker of PCBs for products that come under the brands of Delta, AcBel, Acer, Samsung and many others.
Antec doesn’t develop its own PSUs. Instead, the company uses its brand to offer products from respectable manufacturers. The HCP-1200 (like the above-mentioned Signature SG-850) was created by Delta Electronics.
The PSU has high-quality Rubicon and Nippon Chemi-Con capacitors at its output. Every capacitor is rated for an operating temperature up to 105°C.
The PSU is equipped with the following cables and connectors:
Included with the PSU are:
The cables and connectors are numerous and long, but one of the two mainboard power cables is going to be redundant for most PCs.
Note also that the PSU has three peripheral power connectors but comes with as many as five such cables, so you can choose what cables are suitable for your specific configuration. Considering that there are also fixed PATA and SATA power cables, you should have no problems powering up each of your components.
The PSU specs are up to today’s requirements: 99% of its full output power can be delivered across the +12V lines (there are eight of them here, each with a load capacity of 30 amperes).
The +3.3V and +5V rails have a load capacity of 25 amperes each, for a combined load up to 175 watts. This is going to be more than enough for any modern computer.
The PSU features 80+Gold certification which promises 87% efficiency at 20% and 100% load and 90% efficiency at 50% load.
Working with my APC SmartUPS SC 620, the HCP-1200 was stable at loads up to 406 and 330 watts when powered by the mains and UPS batteries, respectively. The pair switched to the UPS’s batteries normally. When the mentioned load was exceeded, the UPS indicated overload but did not shut down immediately.
The +12V and +5V voltages are quite stable, always remaining within 3% from their nominal values. They are not going to deflect by more than 2% in a real-life computer.
The +3.3V rail is somewhat worse. When there’s a normal load on the +3.3V rail and a high load on the +12V rail, this voltage can fluctuate as much as 4%.
The output voltage ripple is close to the permissible maximum of 50 millivolts on the +5V and +3.3V rails. The ripple is not that strong on the more important +12V rail although the permissible maximum is higher there (up to 120 millivolts).
The HCP-1200 is cooled by a single 80mm fan.
It is a 9AH0812P4G131 model from Sanyo Denki. It’s got seven blades with rounded-off ends. Sanyo Denki fans are generally quieter than average fans from other makers, but the resulting acoustic comfort is going to depend on speed. Even a very good fan can't be silent when rotating too fast.
The fan works at a very low speed until a load of 600 watts, the PSU being almost silent then. As the load increases further, the fan accelerates in a linear manner, being quiet at loads up to 700 watts, audible at 800 watts and downright noisy at higher loads. The maximum speed of 3600 RPM at full load is just unacceptable and also redundant (the difference between the incoming and outgoing air decreases towards higher loads, down to a mere 4°C at a load of 1200 watts).
The PSU is so noisy at near-maximum loads that even the wailing of graphics card coolers seems more agreeable to the ear.
The power factor is typical for active PFC.
The efficiency is quite high: 90.9%, 90% and 85.9% at loads of 20%, 50% and 100%, respectively. However, this PSU is 80+Gold certified which means it must be 87% efficient at full load. Hopefully, the difference is due to some measurement inaccuracies rather than to the PSU’s own fault, yet I do suspect there’s something wrong with the PSU because its efficiency should have increased in the 220V power grid I connected it to during my tests. Our testing equipment can’t be that inaccurate.
Despite its high specified load capacity of 4 amperes, the standby sources copes with its job without any problems.
The Antec HCP-1200 is a high-wattage and high-efficiency PSU which is almost silent at loads up to 50%. However, it is too noisy at near-maximum loads and I also have doubts about its compliance with the 80+Gold requirements in terms of efficiency.
Like the HPC-1200 in Antec’s line-up, the AX1200 is the flagship model of Corsair’s top-end Professional Series Gold. As its name suggests, the series is 80+Gold compliant.
The AX1200 is shipped in a large box that, unfortunately, lacks a carry handle.
There’s a lot of information on the back of the box: a list of power connectors, efficiency and noise diagrams, product specs and descriptions of key features.
The elongated shape of the box and its contents (a pouch with detachable cables, another velvety pouch for the PSU, a pack with screws, cable straps and a sticker with manufacturer’s logo) resemble Seasonic's X Gold series.
Contrary to the obvious conclusion (and unlike the other models of its series which are indeed based on Seasonic's platform), the AX1200 is a Flextronics-based product.
The AX1200 is closer to the classic top-wattage PSU design in its exterior.
It looks ordinary enough with its rough matte-black paint, 140mm fan and honeycomb-mesh grid of the back panel. The rest of the panels are blank. The AX1200 is even longer at 200 millimeters than the above-discussed Antec.
The AX1200 is an all-modular PSU. It has not a single fixed cable.
The interior design of the Corsair is more conventional than that of the Antec, too. There are some things worth noting, though.
The component layout departs from the tradition in some respects: the input capacitors are almost in the center of the case, the intricate heatsinks are unusual for a high-efficiency PSU, and there are unexpectedly small high-frequency transformers in strange packaging here.
The PSU generates +3.3V and +5V voltages by means of DC-DC converters located on two upright daughter cards. There are capacitors and chokes on one side of each card.
On the other side we can see MOS transistors and some small components.
It’s unusual that the DC-DC converter cards are placed on both sides of the two transformers. The more conventional layout is to put them next to each other. Anyway, despite the mentioned layout nuances and unusual transformers, the AX1200 has quite a standard circuit design.
The Corsair AX1200 being more modular than the Antec, the daughter card with connectors is very large. It carries a lot of ceramic capacitors which should contribute to minimizing voltage ripple at the PSU’s output.
This all-modular PSU comes with the following cables:
The graphics card and mainboard cables are sleeved. The peripheral power cables are flat and more flexible. Each cable is labeled with the PSU’s model name, suggesting that shouldn’t use them with other PSUs.
The cables are sufficiently long but the small spacing between the PATA and SATA connectors on the same cable can be a problem. On the other hand, this depends on your system case and its HDD bays. You may even find this spacing more convenient than the traditional 15 centimeters.
Like the Antec model, the AX1200 comes with more power cables than it has connectors: eight cables for six connectors. This gives you more flexibility in configuring the power supply of your components.
The Corsair AX1200 boasts the highest wattage rating of all the PSUs in this review. The others are 1200 watts whereas the AX1200 is 1204.8 watts, and it can deliver all of it across its solid +12V power rail.
The load capacity of the +3.3V and +5V rails is more than enough for any modern PC configuration.
As I’ve mentioned above, the AX1200 is 80+Gold certified.
Connected to my APC SmartUPS SC 620, the AX1200 was stable at loads up to 418 watts when powered by the mains but the UPS reported overload and shut down immediately after the pair tried to switch to the UPS batteries.
The cross-load diagram is similar to the Antec’s except that it’s now the +5V rather than +3.3V voltage that acts as the weak link.
The +12V voltage is almost ideal, always staying within 2% of the nominal value. The +3.3V voltage deflects by more than 3% only when there’s very high load on both the +3.3V and +12V rails.
The +5V voltage is the most unstable of all. It deflects by 4% from its default level in the typical load range of that power rail when there’s also high load on the +12V rail.
As promised by the manufacturer, the high-voltage ripple at full load is very low and meets the requirements of the industry standard.
We can see some voltage spikes on the +12V rail at the double frequency of the power mains. This ripple is within the permissible limits but spoils the good impression from the previous diagram.
The AX1200 is cooled by a 7-blade Yate Loon fan (D14BH-12 part number, 140mm, 2800 RPM).
The good news is that the fan is never close to its maximum 2800 RPM even at full load. The highest speed it can reach in this PSU is about 1700 RPM.
The bad news is that it starts out at a rather high speed of 1300 RPM and accelerates right away.
As a result, the fan is going to be audible even when the computer is idle. This can hardly be made up for by the fact that the AX1200 is quite good in terms of noisiness at full load (compared to same-class products).
As opposed to the Antec, the Corsair PSU gives no reason to question its 80+Gold certification. It is 88.9%, 90.3% and 87% efficient at loads of 20%, 50% and 100%.
Its active PFC device works somewhat better than in average PSUs, keeping the power factor above 99% through the larger part of the load range and reaching 99.8% at the maximum.
The standby source copes with its job but the voltage drop is noticeable at near-maximum load.
The Corsair AX1200 features good electrical parameters and handy modular cables. It is not very loud at high loads but its fan is audible even in idle mode.
Cougar PSUs used to ship bundled with Ascot system cases, so you may be surprised to see this brand in the company of far more famous ones. However, we can really expect competitive solutions from a retail outlet of HEC/Compucase Group that owns the Cougar brand (and Ascot too, for that matter). HEC/Compucase Group is a large OEM maker of system cases and power supplies and now it takes a step onto the retail market.
The PSU comes in a flat cardboard box which is just barely wider than the PSU itself.
The back side of the box shows you a description of the product’s features in four languages, tables with specs and connectors for the 1000W and 1200W models in the series, and the benefits of its cooling system.
Although not a first-tier brand, this Cougar looks quite eye-catching.
It’s colored a nice-looking combination of reddish-brown and black with silvery elements. The sleeved cables are multicolored as well. The punched-out vent grids are honeycomb mesh. The unusual coloring and clever design endow this product with individuality.
The CMX 1200 is a modular PSU. Unlike in most other PSUs of this kind, there is a vent grid even in the connectors panel.
Like the above-discussed Antec, this PSU is 180 millimeters long.
This PSU is not as original in its component layout and circuit design as the two previous models.
It features a classic dual-transformer design. The heatsinks on the power components are rather large but not intricately shaped.
Like the previous models in this review, the Cougar CMX 1200 featured dedicated voltage regulation based on DC-DC converters.
There are Teapo capacitors on the PSU’s output and Panasonic ones at its input. The electrolytic capacitors are all rated for an operating temperature up to 105°C.
The Cougar CMX 1200 is equipped with the following cables and connectors:
Included with the PSU are:
Despite the lack of redundant modular cables that would give you more connection flexibility, this selection of cables and connectors is sufficient for nearly any PC configuration. Even if you spend the cable with three SATA connectors on your optical drive alone, the rest of the cables will be able to power up as many as nine disks. On the other hand, it is not always handy to have a lot of power connectors (even of different varieties) on the same cable.
The cables are long so you should be able to hide them behind the mainboard even in large system cases with a bottom PSU bay.
The only thing that looks odd to me is the second mainboard cable. It is long enough up to its first 8-pin connector but then it continues as a 30cm stretch to a 4+4-pin connector and another 30cm stretch to a 4-pin connector. So, this cable has a combined length of 122 centimeters and as many as three connectors, but most of its length and connectors are not going to be used. I guess it would be better if this cable were replaced with a shorter one with a single 4+4-pin connector, just like in most other PSUs.
I can also criticize the manufacturer for saving on 6+2-pin connectors for graphics card cables. Two out of the six connectors lack those additional 2 pins. Theoretically, the PSU should be able to power any graphics configuration: three single-GPU graphics cards (each of which does not need more than one 8-pin and one 6-pin power connector) or two dual-GPU ones (each with two 8-pin connectors). However, if you only use 8-pin graphics cards, the fixed 6-pin cable will not do anything but take up free space inside your computer.
As opposed to the other PSUs in this review, the Cougar CMX 1200 can deliver only 90% of its total output power across the +12V rail: 1080 out of 1200 watts. Considering the typical power consumption of modern computers on the +3.3V and +5V rails, it will hardly need to output more than 1150 watts even if the +12V rail is fully loaded.
The load capacity of the +5V and +3.3V rails combined is 30 amperes or 175 watts. That’s quite enough for today’s computers.
As opposed to its opponents in this review, the Cougar CMX 1200 complies with the 80+Bronze rather than Gold standard.
Connected to my APC SmartUPS SC 620, this PSU was stable at loads up to 390 watts when powered by the mains but could only switch to the UPS’s batteries at a load of 300 watts.
The manufacturer claims the output voltages to be always within 3% of their default levels, but this promise is only fulfilled for the +12V rail.
The +3.3V voltage deflects by 4% when the load on both the +3.3V and +12V rails is either very high or very low.
The +5V voltage deflects even more: it is due to this voltage violating the permissible limits that the cross-load diagram has a jagged top right corner.
On the other hand, if we take a real-life computer system, the voltages are not going to deflect by more than 3% in it.
The high-frequency voltage ripple is within the norm on each power rail.
The low-frequency ripple at the double mains frequency is noticeable on the +12V rail but meets the requirements of the industry standard, too.
The PSU is cooled by a Cougar PLA14025S12H fan which runs on a fluid dynamic bearing. This is supposed to ensure a longer service life than other types of bearing. The impeller blades are shaped originally. They are almost straight and have slanted ends.
The fan starts out at a speed of 1000 RPM and doesn’t accelerate much until a load of 450 watts. The PSU is close to silent then. After the mentioned threshold the speed begins to increase in a linear manner until 2000 RPM at full load, making the PSU average in terms of noisiness among same-class products.
So, the acoustic properties of the Cougar CMX 1200 are quite acceptable. It is very quiet at low loads and is not going to stand out among the rest of system components at high loads.
The power factor is quite typical for active PFC.
The efficiency is notably, by up to 5%, lower than that of the other tested PSUs at near-maximum loads. However, the Cougar CMX 1200 is but slightly inferior to its opponents at loads up to 50%. It is indeed 80+Bronze compliant.
I can see no problems with the PSU’s standby source.
The Cougar CMX 1200 doesn’t look as impressive as its opponents. Its efficiency is lower, its fan gets audible sooner, and its cable system is not as flexible as that of the other modular PSUs. However, this product comes at a much more affordable price, which may make up for its slightly inferior characteristics.
This high-wattage model from Enhance has been showcased at different expos but hasn’t yet made it to the shops. Let’s see if we should really look forward to it.
At a length of only 160 millimeters, the EPS-1812GA4 is the most compact of the PSUs in this review.
The compactness comes at the expense of modular design. The numerous cables that such a high-wattage PSU is supposed to possess have to be somehow accommodated inside your computer chassis even when not in use.
Otherwise, the EPS-1812GA4 looks ordinary enough with its smooth matte-black paint, 140mm fan, and honeycomb-mesh vent grid of the back panel that lacks an On/Off switch. The rest of the panels are blank.
Like the Cougar model, the EPS-1812GA4 follows the well-established trends with its interior design.
Notwithstanding the small dimensions and high wattage rating, the component density isn’t too high. This is largely due to the PSU’s having only one power transformer.
The characteristic fingered heatsinks hide DC-DC converters that the PSU employs to generate +3.3V and +5V voltages, just like the other PSUs in this review.
There are Nippon Chemi-Con capacitors at the PSU’s output. They are rated for an operating temperature of 105°C.
The EPS-1812GA4 is equipped with the following cables and connectors:
Unfortunately, the main cables are too short for large system cases. This is a regrettable shortcoming in a PSU that is meant for top-performance PC configurations which can hardly be assembled in compact system cases.
Of course, there is also the inevitable downside of the non-modular design: you have to lay all those cables out somehow in your chassis because you cannot remove unused ones.
The EPS-1812GA4 meets today’s requirements with its specs. It can give its full output power across the +12V rail (which is split into four “virtual” lines with a max load of 40 amperes each) and can provide enough power to +3.3V and +5V devices (each of these rails has a load capacity of 25 amperes; their combined max load is 180 watts).
Although there is no official 80+ certification for this PSU, the manufacturer claims it meets the Gold version of that standard.
Connected to APC SmartUPS SC 620, this PSU was stable at loads up to 392 watts when powered by the mains but could only switch to the UPS’s batteries at a load of 280 watts.
The +12V and +3.3V voltages do not deflect by more than 3% from their ideal levels except that the +3.3V voltage gets more unstable when there is unrealistically high load on the +3.3V rail and a high load on the +12V rail.
The +12V rail behaves differently than in most other high-wattage PSUs where this voltage deflects more at low loads and less at high loads. Here, the +12V voltage keeps within 1% from its default level at loads up to 500 watts but fluctuates more at higher loads.
The +5V voltage is the least stable of all, deflecting by 4-5% from 5 volts when there’s a high load on the +12V rail.
The high-frequency voltage ripple is close to the permissible limits on each power rail, occasional spikes even shooting above those limits on the +5V rail.
The same goes for the low-frequency ripple.
Enhance should do something about this parameter as the EPS-1812GA4 barely meets the industry standard.
The PSU is cooled by a DFB132512H fan from Young Lin Tech. It’s an 11-blade 135mm model with a rated speed up to 1700 RPM.
The fan starts out at 720 RPM and doesn’t change this speed until a load of 450 watts. Then it accelerates in a linear manner up to 1400 RPM at 950 watts and maintains this speed until full load. Thus, the fan doesn’t even reach its maximum rated speed. As a result, the EPS-1812GA4 turns out to be the quietest of the four PSUs. It is virtually silent at loads up to 700 watts and does not get uncomfortable even at full load.
The power factor is just what you can expect from a modern PSU with active power factor correction.
As for the efficiency, my tests suggest that this model can meet the 80+Gold requirements even though it lacks official certification.
It is 3.2% and 0.8% more efficient than required at loads of 20% and 50%. At full load it is 0.1% less efficient than necessary, but this may be due to measurement inaccuracies, especially as it is 87.3% efficient only 26 watts short of full load.
The standby source is blameless.
The Enhance EPS-1812GA4 can boast good electrical and acoustic properties, but has short fixed cables and a rather high level of output voltage ripple.
If Enhance can get rid of the mentioned downsides without compromising the model’s quietness, it would be a very good buy.
Unfortunately, I couldn’t find a perfect 1200W power supply in this review. Each of the four tested products has certain downsides.
Each of them fails to some extent in keeping one of the auxiliary voltages (+3.3 or +5 volts) stable when the +12V rail is under high load. The voltages remain within the standard-defined limits but deflect up to 4% from their nominal value, which is rather too much for PSUs of that class and pricing.
As for the noise factor, the Enhance EPS-1812GA4 is just splendid both at low and high loads in this respect. It is also quite as good as its Gold-certified competitors in its electrical parameters except for the high level of output voltage ripple. However, this model is let down by its fixed rather than modular cables which are also too short, especially the mainboard one.
The Corsair AX1200 is handy with its modular design. It is not very loud at high loads and has the lowest level of output voltage ripple. The downside is that its fan is audible even when the computer is idle (that’s not uncomfortable, but modern PSUs are not supposed to produce any sounds when idle). Besides, it turned out to be incompatible with line-interactive UPSes.
The Antec High Current Pro HCP-1200 delivers the most stable voltages of the four tested PSUs. It is also UPS-compatible and quiet at medium loads. However, it is somewhat less efficient than specified according to my tests and is also awfully loud at near-maximum loads.
The Bronze-certified Cougar CMX 1200 is quite competitive, too. With somewhat worse electrical parameters (such as efficiency and the load capacity of the +12V rail) and not as flexible modular design as the Corsair and Antec products have, it is very quiet at low to medium loads and doesn’t get too loud at high ones. Although the CMX 1200 is technically inferior to its competitors in this review, it seems to be a leader in terms of price/performance ratio. It lacks serious downsides while its price is much more affordable.