ATX Power Supply Units Roundup. Part IX

This part of our roundup will be devoted to power supply units with capacity ranging from 450W to 850W. We will check out 7 models from AcBel, Gigabyte, Zalman and Corsair. All the details on their performance and functionality in our extensive article!

by Oleg Artamonov
03/28/2008 | 02:47 PM

Today I will be discussing seven power supply units which wattage is now considered medium, from 450W to 850W to be exact. Well, this positioning is not exactly accurate. Although most of the manufacturers have already released their 1000W PSUs and some of them have reached 1500W, even very advanced PC configurations with a top-end CPU and a couple of graphics cards consume much less than 1000W. A typical home system with a dual-core CPU and one graphics card will find even a 600W PSU somewhat redundant.


The PSU models to be discussed are more or less ordinary in their electric specs but one stands out with its functionality: the Gigabyte Odin GT features a USB interface, quite an uncommon thing for a power supply.

Testing Methodology

Click the following link for a description of our testing methodology, the equipment we use, and a brief explanation of what the specified and tested parameters of power supplies mean. The article is called X-bit Labs Presents: Power Supply Unit Testing Methodology In-Depth. If you feel overwhelmed with the numbers and terms this article abounds in, check out an appropriate section of the mentioned article for an explanation.

You can also check Other section on our site for a complete list of PSU models we have tested in our labs.

AcBel Intelligent Power 560 (510W) and 660 (610W)

Products from AcBel Polytech have already been reviewed by us before. And today I have two new models from the company’s Intelligent Power series. I’ll talk about them both together as they are very similar between each other.

The PSUs have standard-size cases painted a matte black.

AcBel IP 560

The internal design is typical for a medium-level modern PSU: joint voltage regulation and active PFC.

AcBel IP 660

The 560 and 660 models resemble each other. They are both based on the same PCB, and the ratings of most components coincide. These two PSUs differ significantly from the Intelligent Power series models we reviewed earlier, though. The new PSUs are obviously roomier, some components having become smaller. It doesn’t mean the design has become cheaper and simpler – this effect can be achieved by modernizing the components, for example by increasing the operating frequency of the PWM-regulator. Particularly, the PFC choke based on an E-type core installed in the previous models is now replaced with a more compact toroidal one. Some of the passive components accompanying it have moved from a small individual PFC controller card to the main PCB.

The PFC and main-regulator controllers are based on a Fairchild FAN4800 chip, a version of the popular ML4800.

The model names of the PSUs seem to reflect the so-called peak output power, i.e. the load the PSU can work with for one minute only. The continuous load (the PSU can work with it for an infinitely long time) marked on the label is 50W lower (for the 560 model, it is 491.5W + 18.5W = 510W). On the other hand, the PSUs can yield almost all the power across the +12V rail, which is the most loaded rail in a modern PC.

The 560 model uses a Protechnic Electric MGA12012MS-A25 fan (120x120x25mm). Unfortunately, products from this firm are not held in high repute among people who prefer silence.

The senior model has a more powerful fan, the MGA12012HS-A25 model. Some of it is covered with a piece of plastic to drive the airflow into the back part of the PSU for uniform cooling of the components.

Both PSUs come with the same selection of cables and connectors:

That’s a good selection. The PSUs can power up two graphics cards and offers enough of SATA connectors. Moreover, the SATA plugs are located on two different cables for powering both a DVD drive and a HDD that are usually located rather far from each other.

These PSUs worked together with an APC SmartUPS SC 620 at loads up to 370W (when powered from the mains) and 330W (from the batteries). The UPS switched to the batteries normally. Both PSUs worked at full load without problems.


The output voltage ripple is normal (the allowable limits are marked to the right of the oscillogram). There was also a low-frequency (100Hz) pulsation on the +12V rail, yet its amplitude was negligibly small.

The cross-load characteristics of the junior model are normal for its class (to remind you, these models have joint voltage regulation). In a typical modern PC (that puts a load of 20-30W on the +5V and +3.3V rails combined and the rest of the total load on the +12V rail) the +5V and +3.3V voltages are going to be near the nominal values while the +12V voltage may sag by 3% in especially advanced configurations, e.g. systems with a quad-core CPU and two graphics cards (or a dual-chip card like the Radeon HD 3870 X2).

The senior model doesn’t differ much from the junior one in this test.

The 560 model’s fan speed is lower than 800rpm at loads below 200W. Thus, the PSU is going to be absolutely silent in a real PC when the system is idle. At higher loads the speed is increasing steadily but the PSU is still rather quiet until a load of 300W. After that, the noise of the fan’s impeller and of the airflow becomes audible.

The senior model is similar in its noise characteristics to the junior one despite the more powerful fan: the speed is almost the same at low loads and grows up linearly depending on load in the same manner. This indicates a good implementation of automatic speed management.

The junior model features a good efficiency, about 83%, but the power factor is surprisingly low. PSUs with active Power Factor Correction usually have a power factor of 95-99%. This parameter is of little importance for the end-user, though.

The senior model has similar results except that its efficiency drops below 80% at full load.

The Intelligent Power 560 and 660 power supplies from AcBel are rather typical representatives of the middle class. They easily deliver the specified parameters and work quietly at low loads (which is good for modern PCs whose power consumption is low in idle mode).

You should realize that this middle class has been formed as the result of the PSU manufacturers’ rush towards higher and higher wattage ratings whereas real-life systems, except for enthusiasts’ configurations with Freon coolers etc, do not need that much power. That’s why these AcBel power supplies with wattage of about 500W will be an optimal choice not only for mainstream PCs but also for advanced gaming systems that include senior CPU and graphics card models. For example, Intel’s dual-processor Skulltrail platform consumed slightly more than 400W in our tests.

Corsair CMPSU-750TX (750W)

Over a year ago we tested a Corsair PSU with a somewhat lower wattage rating. That was the CMPSU-620HX model and it left a very nice impression then. Corsair doesn’t produce PSUs itself, though. The company ordered the CMPSU-620HX from Seasonic while the CMPSU-750TX model we are going to discuss today is manufactured at Channel Well (CWT) facilities.

The PSU comes in a black-and-orange box whose label announces a 5-year warranty. This may be the decisive factor for some users’ shopping decision – you are sure to have heard stories about power supplies failing after two or three years of work. The sticker and the warranty refer to the American market only, though. The warranty term may differ in your location.

There is a nice surprise waiting inside the box: the PSU is stored in a black velvet pouch rather than in a plastic bag. Well, it’s nice indeed, but there’s no practical value from it.

The PSU is somewhat longer than the standard ATX power supply. Its case is painted a matte black.

It’s clear the case could have been shorter if it were not for the 14cm fan: there is enough of free space between the rear panel and the PCB. On the other hand, this space can be used for a PCB with connectors if Corsair decides to release a detachable-cable version of this PSU.

The CMPSU-750TX features active PFC and dedicated voltage regulation. These technologies have become a de facto standard in modern top-class PSUs. The load-bearing elements are distributed among three heatsinks that are painted black (this is only done for aesthetic purposes: the color of the heatsink has no effect on the heat-transfer efficiency of active cooling).

The PSU is equipped with a 140x140x25mm fan (Yate Loon D14BH-12). According to the manufacturer’s website, its rated speed is 2800rpm. The real speed of the fan in this PSU will be measured below.

The number in the PSU name coincides with its maximum continuous output power – 750W. It can yield up to 720W across its +12V power rail (which is “monolithic”, i.e. not split into multiple output lines).

The PSU offers the following cables and connectors:

That’s a good selection of connectors. There’s everything you may ever want from your PSU.

Unfortunately, the CMPSU-750TX had some problems in the UPS compatibility test. Together with an APC SmartUPS SC 620 it worked at loads up to 365W (from the mains) and 350W (from the batteries). This result would be good if it were not for one thing: when the load was higher than these values, the UPS didn’t just report overload but shut down instantly.

The PSU worked normally at full load.

The high-frequency output voltage ripple is within the norm. No low-frequency pulsation was observed in this test.

The cross-load diagram looks very good: the PSU copes easily with every load balance. The +12V voltage never deflects more than 2% from the nominal value. That’s dedicated voltage regulation for you!

Alas, this PSU proved to be rather noisy. The fan is never slower than 1100rpm but it is audible even at that speed in a quiet PC. The fan speed grows up linearly at loads above 350W, reaching 2000rpm at the maximum. The CMPSU-750TX seems to be average in terms of noisiness. It will satisfy most users, but won’t be liked by people who prefer silent computers.

The efficiency and power factors are all right, reaching 85% and 98%, respectively.

So, the Corsair CMPSU-750TX can be recommended for owners of very advanced PC configurations, for example those that include two graphics cards, but with two limitations: if you plan to use an UPS, you should select the latter with a higher wattage rating than actually necessary. And second, this PSU may not suit people who have a quiet PC. Otherwise, this is a good model with high wattage, superb stability of the output voltages, and a rich selection of connectors.

Gigabyte Superb 550 GE-P450N-C2 (450W)

A major manufacturer of mainboards, Gigabyte has diversified its business recently, starting up PSU production. Well, Gigabyte is not the actual maker of Gigabyte-branded PSUs. The inexpensive Superb 550 model is made by AcBel Polytech.

The PSU is shipped in a black-and-white box with “550W” in large print and “Peak performance” in small print. These two captions should be understood together: 550W is the peak output power of the PSU, not the continuous one.

The device has a matte black case of the standard ATX size. It is not very easy to take it apart: the two halves are fastened with screws as well as with the sticker label.

The input voltage switch is a sure indicator of the lack of an active PFC device because power supplies with active Power Factor Correction support either 220V mains voltage (without the option of switching) or the entire input voltage range from 90V through 264V.

Although made by a third party, the PSU is obviously designed especially for Gigabyte. The PCB is painted Gigabyte’s traditional blue.

The components are very dense inside due to the small size of the PCB. You can see the latter doesn’t take up all of the PSU’s interior. The heatsinks have a copper-like color, but are actually made from anodized aluminum. The circuit design is quite ordinary for today: an UC3843-based PWM controller, a TNY277P-based standby regulator, no active PFC, no joint voltage regulation. To remind you again, this is a junior model in Gigabyte’s product line-up.

The PSU is equipped with a 120x120x25mm fan (Protechnic Electric MGA12012HS-O25). Despite the translucent plastic, the fan is not highlighted. About 40% of its area is covered with a piece of plastic film for a more uniform distribution of air inside the PSU.

According to the label, the PSU is intended for a continuous load of 450W, i.e. 100W lower than the number on the box. It has two “virtual” +12V lines and can yield up to 30A (360W) across them – this is 40W lower than ATX12V Power Supply Design Guide 2.2 recommends for PSUs of such wattage.

The PSU has the following cables and connectors:

A 6-pin → 8-pin adapter for the graphics card is included into the box.

This selection of connectors is up to the PSU’s positioning. I would note the four SATA connectors on two cables again: this allows easily connecting both a DVD drive and a HDD.

Together with an APC SmartUPS SC 620 this PSU worked at loads up to 300W (from both the mains and the batteries) and the switching to the batteries was performed without problems. Well, it is only PSUs with active PFC that may have potential problems with UPSes – the Superb 550 doesn’t belong to that class. The PSU also passed the full load test normally.

The output voltage ripple at full load is far within the permissible limits.

As the load on the +5V and +3.3V rails grows up, the respective voltages sag and violate the permissible 5% deflection. But considering that these rails are not loaded heavily in modern PCs, the only real drawback I can see is that the +12V voltage sags at loads of over 250W. Well, even a gaming system with a Core 2 Duo processor and one graphics card like GeForce 8800 GT consumes less – so you should have no problems with this PSU.

The fan works at a constant speed of 850rpm until a load of 170W and accelerates steadily hereafter. As a result, the PSU is very quiet at low loads and average at loads over 200W. Interestingly, the above-discussed PSUs, also manufactured by AcBel and with similar fans, proved to be quieter in practice.

The efficiency barely reached 80%, which is a very modest result for a modern PSU. The power factor is no higher than 0.65.

Gigabyte’s new PSU is a good entry-level product. It doesn’t boast exceptional specs or functionality, but shows no problems within the scope of its intended applications. Featuring good quality of manufacture, quiet operation and low loads, sufficient wattage (even for gaming systems), this PSU should be a good choice for both office and home PCs if you find its price reasonable.

Gigabyte Odin Pro GE-M550A-D1 (550W)

While the previous model belonged to the low-end market sector, the Odin Pro is quite another level notwithstanding the same number on the box.

Like the Superb 550, this PSU is not made by Gigabyte itself. The actual manufacturer of it is Channel Well (CWT).

The PSU is shipped in a colorful black-and-green box. There is no reference to peak performance on it – the Odin Pro is indeed rated for an output power of 550W.

The PSU has got a matte black case that is somewhat longer than the standard ATX model in order to accommodate the large 14cm fan. It may seem that the case has vent grids not only in the external but also in the side panel, but the latter is actually sealed with translucent plastic film on the inside. The perforation of the side panel is merely a decorative element.

The PSU has high component density and large well-ribbed heatsinks. Note the four LEDs fastened on the ribs: this is the highlighting of the fan.

This photo shows that the perforation of the side panel is covered with plastic film. You can see it reflect the anodized aluminum of the heatsinks and the white-blue sticker “Japan made capacitor”.

The PSU uses a 140x140x25mm fan (Yate Loon D14BM-12).

The label says the PSU is indeed rated for 550W, and it can yield 492W across its +12V rail which is split into four virtual output lines. The purpose of each line is indicated in the small table in the bottom left.

As opposed to the above-discussed products, the Odin Pro features detachable cables. The connectors for them are located at the back panel. There is also a switch there to turn on the blue highlighting of the PSU.

So, the PSU is equipped with the following cables and connectors:

Included with the PSU are:

The mainboard connector is equipped with a rubber “head”. The other connectors are ordinary enough.

Alas, the PSU proved to be incompatible with our UPS. Together with an APC SmartUPS SC 620 this power supply worked at loads up to 360W when powered from the mains. But when powered from the batteries, the UPS reported overload even at a load of 250W.

The PSU passed the full-load test successfully, though.

The output voltage ripple is within required limits.

The Odin Pro features dedicated voltage regulation as is confirmed by this test. None of the voltages deflect more than 3% from the nominal value even at greatly misbalanced loads. That’s an excellent result.

The fan maintained a constant speed of 980rpm up to a load of 400W. Although this is not the lowest speed I’ve seen, the Odin Pro can be viewed as a very quiet PSU.

The PSU is 85% efficient through a wide load range, and its power factor is 0.99. The latter fact is somewhat spoiled by the incompatibility of the Power Factor Correction device with our UPS.

So, Gigabyte’s debut on the PSU market can be considered a success. While the Superb 550 is a rather unexciting ordinary model, the Odin Pro, without a doubt, is a more serious product. It’s got a quiet fan, detachable cables, a nice selection of connectors, and very stable output voltages. The only thing I complain about is the poor compatibility of this PSU with uninterruptible power supplies.

Gigabyte Odin GT GE-S550A-D1 (550W)

This PSU is similar to the above-discussed Odin Pro in its parameters, yet it is actually unique. It’s the first time we ever test such a PSU in our labs.

You may remember our review of the AcBel LCD Power Supply that was shipped with a small module to be installed into a 3.5” bay. The module reported the current status of the PSU such as load, temperature, and fan speed. A remarkable feature, the module could be connected to a USB port so that its data could be read by software.

The Gigabyte Odin GT develops this approach much further. This PSU has a USB interface it can be connected to the PC it powers up with. As opposed to the AcBel PSU, there is no need for a dedicated module, while the software monitoring and configuring options for the PSU have been expanded greatly. Running a little ahead, I should confess these options are actually exhaustive. It’s hard to imagine anything you could add more into your PSU.

In my tests I connected the PSU to a USB port of the PC configured like follows:

A CD with the control program, called Power Tuner, is included with the PSU. You don’t need a driver to power up the PC with this power supply, though.

Having connected the PSU to a USB port (it is identified by the OS as a USB HID) and installed Power Tuner, I saw the following:

Thus, Power Tuner reports real-time information about:

That’s a lot of info indeed. You can even learn not only the total load but the load on each of the power rails individually! I wonder how the PSU manufacturers will now be explaining the customer the need to buy 1000W and higher PSUs.

Power Tuner is accurate enough. Its showings differed by slightly from the results I obtained on our testbed, especially for large numbers (wattages higher than 100W and currents higher than 5A).

Besides the monitoring screen, Power Tuner has two more sections:

As you can see, the Odin GT not only provides information about the PSU’s status but also allows to control the speed of its fan. The latter has two operation modes: constant speed or a linear growth of speed depending on PSU temperature. Power Tuner allows you to select the specific speed for the first mode or the point of switching into the second mode. Besides three preset variants you can specify both parameters manually by moving the sliders near the fan speed graph.

Choose the necessary mode and click Ok to send your choice to the PSU.

Finally, the third section of the Power Tuner tool allows setting thresholds for the warning signal. As you can see, the thresholds can be based on total load, on currents and voltages of individual outputs, fan speed or PSU temperature.

Unfortunately, Power Tuner offers abundant options in a very inconvenient interface. The program window is overloaded with various decorations that distract your eyes from the data and slow the GUI down – the program switches between its screens with visible jerks.

I hope Gigabyte’s programmers will polish this tool off so that its pretty appearance wouldn’t affect the ease of use. And now let’s take a look at the actual PSU.

The Odin GT comes in a colorful black-and-violet box. There’s text about the Power Tuner tool on the face side of the box. So if you want to buy this PSU due to its ESA support, you won’t make a mistake when shopping.

The Odin GT is practically the same as the above-discussed Odin Pro: a black matte case of nearly standard ATX size.

The two PSUs are almost identical inside, too. That’s not surprising as their electrical parameters are the same while the Odin GT’s support of ESA technology is the only point of difference.

The USB controller and the monitoring system are placed on an individual card near the side panel of the case. That’s where you can see the difference from the Odin Pro quite clearly: the side card of the Pro version is about half the size of the same card in the GT version.

The back panel now offers not only connectors for power cables but also connectors for various external sensors. As I noted above, the PSU can report information about four external thermal sensors and one fan via its USB interface.

The fan highlighting switch is located nearby but you can also turn it off with the Power Tuner tool.

The PSU is equipped with the following cables and connectors;

Included with the PSU are:

Thus, the PSU can be connected either to an onboard USB port of the mainboard or to an external port (using the included extension cord).

The PSU is rated for a total load of 550W. It can yield 492W via its +12V power rail.

With all the similarity in their designs, the Odin GT is perfectly compatible with UPSes, unlike the Odin Pro. Together with an APC SmartUPS SC 620 the power supply worked at loads up to 360W (from both the mains and the batteries). There were no problems with switching to the batteries.

The PSU also worked well at its full output power, 550W.

The output voltage ripple is within the permissible limits.

The cross-load characteristics of this PSU are superb. The industry standard allows the voltages to deflect by 5% from the nominal values, but the Odin GT only exceeds a 2% deflection at extremely high or extremely low loads.

I measured the speed of the fan having selected the Normal mode in Power Tuner. The speed was about 830rpm at loads up to 270W. Then it started to grow up steadily, reaching 1300rpm at the maximum. So, the PSU is very quiet even without manual adjustments.

I also made sure that the switching of fan modes in Power Tuner and the manual selection of the fan speed in the same program had an immediate effect. The minimum and maximum speeds of the fan you can select are 830rpm and 2000rpm, respectively.

The PSU is over 85% efficient. Its power factor is as high as 0.99.

I think that such technologies, which make it much simpler to build powerful, reliable yet quiet PCs, are even more important that the traditional performance growth estimated in hertz, bytes and watts. If this approach is not limited to a few expensive models, but takes off for real, PC integrators and users will get an excellent tool for measuring the appropriateness of the PSU for a particular PC system. The myths about the necessity of extremely-high-wattage power supplies exist only because it’s hard to perform such a measurement.

The perspectives of an advanced monitoring system are clear even with the first such PSU we’ve ever met with. The Gigabyte Odin GT easily surpasses “smart” models with the indication of consumed power and fan speed control, leaving no chance to them at all. Two capabilities of the Odin GT are especially valuable: the manual selection of the fan speed allows to make an optimal choice between cooling efficiency and quiet operation. The monitoring of currents on the different power rails helps you see if this PSU is appropriate for your system.

I guess the addition of such a system into the PSU is not going to make the latter much more expensive to manufacture. A universal monitoring and control module can be based on one, rather inexpensive, microcontroller with a minimum of accompanying elements.

One thing I’d like to complain about is the software included with the Odin GT. Its clumsy and slow interface doesn’t make the user’s experience enjoyable.

Talking about the Odin GT, I can also recall the recently announced ESA technology from Nvidia. It extends such an approach to all of the PC’s vital components, including the power supply. In Nvidia’s vision, the existing various software and hardware monitoring and control features, often incompatible with each other, should be replaced with a unified open architecture that would allows controlling and regulating the thermal, electric and acoustic parameters of the PC. In other words, it would keep track of the temperature of each component and adjust the fan speed accordingly as well as warn the user about possible failures due to overheat or lack of power. Although the Odin GT doesn’t belong to the ESA architecture, its concept is very similar and provides a preview of how transparent a modern PC can be with such technologies.

Zalman ZM850-HP (850W)

Famous for its cooling solutions, Zalman has been producing power supplies for a few years already, but we don’t review them often. That’s because Zalman doesn’t try to fill the market full with numerous versions of its power supplies. The company offers few models, yet none of them has ever got a negative report from us.

The ZM850-HP is interesting for the breakup for the long-time collaboration between Zalman and FSP Group. Judging by the appearance and internal design, this PSU seems to be manufactured by Enhance Electronics. I don’t say it for sure because the actual manufacturer is not indicated anywhere. The UL certificate number on the label belongs to Zalman and there are no marks on the power supply’s PCB.

The PSU comes in a large black cardboard box which contains two smaller packages: a cardboard box with a PSU and a set of detachable cables.

The ZM850-HP is the only PSU in this review to be much larger than a standard ATX power supply. It is as long as 210mm. On the other hand, it has a higher wattage rating than the models described above.

The PSU features a dual-transformer design. To remind you, this design doesn’t itself provide some special wattage or stability. It only allows to replace one large transformer with two smaller ones, which often simplifies the overall component layout of the PSU. But the main feature that distinguishes the ZM850-HP from its opponents is the cooling system with heat pipes and heatsink at the back panel.

The concept of the cooling system is clear from the photos above: both heatsinks (with the power transistors of the main regulator and PFC on the left, and with output diode packs on the right) do not have any ribbing at all. Their heat is transferred to the third heatsink, made up of thin plates and located near the external vent grid of the PSU. From a theoretical standpoint, this cooling solution has both pros and cons – you’ll see how good the ZM850-HP is in practice shortly.

The PSU is cooled with a Zalman ZF1425ATF fan (140x140x25mm).

Having a total wattage of 850W, the PSU can yield up to 720W across its +12V rail which is split into six virtual output lines. The text to the right of the allowable load table specifies which connectors belong to which 12V line.

Besides eight connectors for detachable cables, the rear panel has a switch marked as Standby Noise Suppressor. The manufacturer doesn’t tell what this switch exactly does, so I had to find it out by myself. It was easy: in the On position, the switch sends a 20Ohm load to the output of the +5V standby source. Without any load the PSU emits an irritating rattling sound due to an obvious reason: switching power supplies work poorly without a load. So if your mainboard produces a sufficient load on the standby source and your PC doesn’t make any undesired sounds, you can leave the switch in the Off position. But if the PC begins to buzz quietly when you shut it down, you can set the switch to the On position to get rid of that sound. Note that the PSU’s power consumption in standby mode will increase by 1.25W after your doing so.

The PSU is equipped with the following cables and connectors:

Included with the PSU are:

A splitter from one Molex to two fan connectors (a +12V and a +5V one) is included with the PSU.

Together with an APC SmartUPS SC 620 this power supply worked at loads up to 366W (from the mains) and 315W (from the batteries). The switching to the batteries was performed without problems.

The PSU passed the full-load test easily.

The output voltage ripple at full load is within the normal range.

Like most PSUs with dedicated voltage regulation, the ZM850-HP draws a cross-load diagram with a lot of green. The +12V voltage barely deflects more than 1% from the nominal value. The +5 and +3.3V voltages are less stable, yet it is only at nearly extreme loads that they deflect much from the nominal values.

The fan was rotating at a constant speed of 720-730rpm at loads up to 700W! That’s a record-breaking performance. I even got some apprehensions during the test about whether it worked at all. It’s only when the load was nearly maximum that the speed began to grow up. As a result, the PSU is not just quiet. It is silent. You can’t hear the fan at such a low speed unless you put your ear right next to it.

The tradeoff of the quiet operation is high temperature, of course. There was a 20°C difference between the air temperature at the input and output of the PSU. It’s hard to tell how this high temperature can affect the reliability of the PSU especially as its internal space heats up less than with the classic component layout because the heatsink has been moved to the external panel of the case.

The PSU is 87% efficient at a load of 350W. Then it lowered somewhat, yet remained above 80% all the time. The power factor was 0.98-0.99 through a wide range of loads.

Well, Zalman’s decision to cooperate with Enhance instead of FSP Group can now be understood. FSP’s models have provoked some questions recently (see this review for details) whereas the ZM850-HP makes a very positive impression with its good electric parameters as well as quietest work. It has rather large dimensions but users whose PC really needs an 850W power supply surely don’t use cramped system cases.


This test session has been a calm one. Every power supply I tested for this review delivered the characteristics specified by their manufacturers and showed quality that matched their price category.

Of course, the Gigabyte Odin GT stands out among the other products as it boasts a full-featured system of monitoring and control. If such technologies take off for real, this will be one more step to transforming the PC from a black box (as it is today in some aspects even to professionals) into a system whose functioning is obvious and transparent. At least, the Odin GT makes it very easy to solve the problem of noise from your PSU and of the appropriateness of the PSU for your particular PC configuration. The question “how many watts do I need for such a system?” is the most frequently asked one at every PSU-related forum after all. Hopefully, such technologies will soon be available not only in expensive PSUs but also in mainstream models.

The products from Corsair and Zalman are interesting, too, in different ways. The Zalman ZM860-HP operates extremely quietly while the Corsair CMPSU-750TX has standard ATX dimensions and is cooled significantly better.

The PSUs from AcBel and Gigabyte – the junior model in Gigabyte’s line-up is actually manufactured by AcBel, though – seem to be rather inexpensive but high-wattage, functional and quiet devices. The only thing I don’t quite like about these PSUs is that both companies wrote the peak, rather than continuous, output power into the product names. So, AcBel added 50W to its products while Gigabyte added as much as 100W to the Superb 550.

Anyway, Gigabyte’s debut on the PSU market should be considered a definite success. All the three PSU models from this brand that I have tested demonstrated very good results over the entire test session.