Cooler Master Power Supply Units Review: Is One Number Important?

Today we are going to talk about two 1 kW power supply units from Cooler Master that have practically identical model names (one digit difference), the same market positioning and identical wattage. They both belong to the Silent Pro family, though come from two different generations.

by Dmitry Vasiliev
09/28/2012 | 10:57 AM

Power supply units for computers have been evolving incessantly, even though not very fast. A decade ago a 70% efficient PSU was the norm but now even 80% looks like an inferior parameter whereas 90% provoke no sensation because we’ve seen 90% efficient PSUs aplenty already. The best way to see this progress is to compare a couple of PSUs from the same brand, of the same wattage and even from the same product series, but belonging to two different generations.


So, today we’re going to test two Cooler Master PSUs (their actual makers are different) which are identical in their wattage rating and market positioning but very different in their date of manufacture. The Silent Pro M was released in late 2009 and the Silent Pro M2 in early 2012.

These are 1000W units which are rather popular among users of high-performance PCs but not as expensive as PSUs of higher wattage that may only be really called for by very powerful overclocked configurations. The 1000W model was the topmost one in the Silent Pro M series whereas the newer Silent Pro M2 is crowned by a 1500W PSU, the 1000W model being one step lower in the hierarchy.

These two products are available for about the same money as of our writing this (the newer model is just a little more expensive on average), so this comparison makes practical sense.

Testing Methodology

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 called 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.

Cooler Master Silent Pro M 1000W

The older of the two 1000W PSUs to be discussed comes in an eye-catching packaging.

The matte wrapper and the originally shaped box help attract a casual shopper’s eye.

Instead of opening up in the conventional way, the box unfolds to both sides, letting you access its contents. The accessories are numerous.

Besides basic accessories (mounting screws, a mains cord and a user manual), we can see a couple of vibration-absorbing pads for the PSU bay (for the front and back panels of the PSU case) and a fabric pouch for the modular cables.

Exterior Design

The exterior of the Silent Pro M 1000W is no less original than its packaging. The top panel is sunken in above the fan and is covered by a curved fan grid with a Cooler Master logo in the center. There are two types of connectors for modular cables which differ in color. The tabs on the side panels help them hold tighter.

The back panel features an extruded vent grid and there’s a manufacturer’s emblem on the bottom panel.

Circuit Design

Although the PCB is marked as Cooler Master, there are some unmistakable features about the interior design of this PSU that point at FSP as its actual maker.

The component layout is almost identical to that of FSP’s Epsilon/Everest PSUs, although the design of the modular connectors card is different.

The Silent Pro M 1000W offers the same basic functionality as its FSP cousins: active PFC and no dedicated voltage regulation.

Besides the shape and size of the heatsinks and the color of the PCB, the only notable difference from the original FSP products is that the Silent Pro M 1000W has a small daughter card with a PWM/PFC controller CM6802SAHG.

The second daughter card, located near the mains connector and covered by a yellow insulating screen, carries a supervisor chip PS224.

As indicated on the product box wrapper, the PSU features Japan-made electrolytic capacitors. The components at the output are manufactured by United Chemi-Con and Nichicon and enjoy an excellent reputation.

Cable and Connectors

The Silent Pro M 1000W is equipped with the following cables and connectors:

Included with the PSU are:

The PSU offers enough power connectors, perhaps even too many when it comes to the graphics card ones: the six 6+2-pin connectors are going to be enough even for a 3-way SLI configuration, so the splitters will hardly be ever required.

It is good that there are different cables with SATA and PATA power connectors because this gives the user more freedom in powering his components.

The cables are conveniently flat, soft and flexible.

The only thing we can complain about is that there is no solid 8-pin CPU power connector. Each of the two connectors consists of two 4-pin halves. The cables are long enough to be hidden behind the mainboard in almost any system case with a bottom PSU bay.


The specs are normal for a modern PSU. Most of the output power can be delivered via the +12V rail. The load capacity of the +3.3V and +5V rails is high at 183 watts. The standby source can cope with loads up to 3 amperes, as is typical of PSUs of such wattage.

The Silent Pro M 1000W features 80 PLUS Bronze certification.

UPS Compatibility

Working together with our SmartUPS SC 620, this PSU was stable at loads up to 358 watts when powered by the mains but could only switch to the UPS’s batteries at 285 watts.

Cross-Load Voltage Stability

We had formed a very favorable opinion about the Silent Pro M 1000W until our practical tests. Unfortunately, its performance in the cross-load voltage stability test was far from perfect.

The most important +12V voltage is stable at low loads, remains within 3% of the required level at medium loads, and goes beyond 4% at high loads. Moreover, it is outside the permissible range when the load on the other power rails is low.

The +5V voltage is out of the required range when there’s a very low load on the +12V rail or when the combined load on the +3.3 and +5V rails is above 120-130 watts (although their specified load capacity is 183 watts). This is not a big problem, though, since modern computers can hardly load the +3.3 and +5V rails by more than 50-60 watts.

The +3.3V rail is the most stable of all. Its voltage is always within the permissible range. It is only at low loads on all the power rails that the +3.3V voltage is more than 3% off the required level.

The Silent Pro M 1000W is overall rather poor in this test, and expectedly so. The similarly designed 1010 W FSP Epsilon reviewed before didn't do that well here too, to put it mildly.

Output Voltage Ripple

The high-frequency voltage ripple is within the norm, making the Silent Pro M 1000W better than the above-mentioned FSP Epsilon 1010W again. There are, however, occasional voltage spikes above the permissible level on the +3.3V rail.

We can see the same picture at the double frequency of the mains.

Temperature and Noise

The Silent Pro M 1000W is cooled by a 7-blade 140mm Power Logic fan (PLA14025S12H). It is half-covered by a plastic screen to optimize air flows inside the PSU.

The fan starts out at about 1000 RPM and keeps this speed until a load of 700 watts. After that it accelerates linearly up to 1930 RPM at full load.

The Silent Pro M 1000W is comfortable acoustically at most loads. Its fan only makes itself heard at loads above 800 watts. The rapid acceleration of the fan at near-maximum loads makes the PSU rather noisy compared to modern 1000W models but, considering that users prefer PSUs that have some reserve of wattage relative to their PC configuration, the Silent Pro M 1000W is indeed going to be silent most of the time.

Efficiency and Power Factor

The PSU is 85.9%, 88.3% and 82.9% efficient at the reference loads of 20%, 50% and 100% and thus meets the 80 PLUS Bronze requirements. Its peak efficiency of 88.6% was observed at a load of 422 watts.

The power factor is about 98% at high loads, which is normal for a PSU with active power factor correction.

Standby Source

The standby source does its job without a problem.


There are a lot of advantages about the Silent Pro M 1000W: good accessories, original exterior design, handy modular cables, low output voltage ripple, high efficiency, quiet operation (except at near-maximum loads) and an affordable price. However, these numerous advantages are negated by one and very serious downside. It cannot deliver stable voltages.

Cooler Master Silent Pro M2 1000W

The packaging of the newer series looks ordinary:

Instead of the unfolding package we now have a standard box without a wrapper or a carry handle.

The accessories now only include the bare minimum: mounting screws, a mains cord and a user manual.

Exterior Design

The newer series is simpler and more conventional in its exterior design. The selection of connectors has changed, too.

As you can see, the out-of-box sample of the PSU turned out to have a stained and loosely fitted faceplate above the modular connectors. This small defect didn't affect its operation, though.

The vent grid on the back doesn't bulge anymore and there's no Cooler Master emblem on the bottom panel. There’s a specifications table instead of the emblem on the new PSU.

Overall, the appearance and accessories of the Silent Pro M2 1000W are indicative of the manufacturer's desire to cut the manufacturing cost. We don't mind as long as this desire doesn't lead to a worsening in the product’s technical properties.

Circuit Design

The fingered heatsinks betray the actual maker of this PSU despite Cooler Master’s branding. It is unmistakably an Enhance.

The basic functionality has remained the same notwithstanding the different platform: active PFC and no dedicated voltage regulation. The PSU doesn’t have such advanced features as DC-DC converters or an additional choke to regulate the +5V voltage.

The component density is higher compared to the predecessor and we cannot read the marking on the controller chips installed on the broad daughter card behind the modular connectors.

The only chip we could identify was the standby PWM-controller A6062H. It’s located on the main PCB next to the standby voltage converter.

There are different brands of capacitors at the output. Well-reputed Teapo components stand next to less renowned Taicon ones. Taicon doesn’t have a good reputation despite the “Nichicon Family” reference you can see at the manufacturer’s website.

Cable and Connectors

The Silent Pro M2 1000W is equipped with the following cables and connectors:

Included with the PSU are:

Oddly enough, our sample of the PSU comes with a SATA power cable that has only three connectors with increased spacing between them whereas the Cooler Master website talks about a total of 12 SATA connectors (our cables have only 11). By the way, the 850W model in this series comes with a SATA power cable with four connectors and increased length (76+10+10+10 cm) instead of the last cable in the list above.

As for the selection of connectors and cables we have here, the downsides of the older model have been corrected but in a rather inappropriate way.

There are six power connectors for graphics cards now, with no splitters in the box, which means that you can still power up to three graphics cards with one 8-pin and one 6-pin connector each. The problem is that the Radeon HD 7970 is the only top-performance single-GPU card that has this configuration of power connectors whereas Nvidia's GeForce GTX 600 series and AMD's other HD 7800 and HD 7900 models usually come with two 6-pin connectors. So, you can't power even two such cards without adapters because three out of the six connectors are solid 8-pin things.

The connectors on the CPU power cables are now solid 8-pin ones, too, so you’re going to have problems powering a mainboard with a 4-pin CPU power connector. These cables have got shorter and can't be hidden behind the mainboard in some large system cases with a bottom PSU bay.

So, the cable system is inferior to the older model’s, although it is quite satisfactory for a modern PSU except for the inadequate selection of graphics card connectors.


The specs are identical to those of the previous model except that the combined load capacity of the +3.3V and +5V rails is rounded off from 183 to 180 watts.

Thus, the only notable difference of the newer PSU is that it is certified for the stricter 80 PLUS Silver requirements.

UPS Compatibility

Working together with our SmartUPS SC 620, this PSU was stable at loads up to 410 watts when powered by the mains but couldn’t switch to the UPS’s batteries even at 280 watts.

Cross-Load Voltage Stability

You forget about the scanty accessories and somewhat higher price when you check out the electrical parameters of this PSU compared to its predecessor.

The +12V voltage is perfect. It is within 2% of the required level at most loads.

The +5V voltage is more than 2% off the required level only when there’s a near-maximum load on the +12V rail.

The +3.3V voltage is the least stable of all. It can be 3% off when there’s a high load on the +12V rail.

Overall, the Silent Pro M2 1000W is very good in the cross-load stability test for a PSU without dedicated voltage regulation. Many PSUs that have the latter feature perform worse in this test.

Output Voltage Ripple

The high-frequency output voltage ripple is somewhat stronger than with the previous model, but remains within the permissible limits. Moreover, there are no high voltage spikes that could be observed with the Silent Pro M.

The low-frequency voltage ripple is only noticeable on the +12V rail.

Temperature and Noise

The Silent Pro M2 1000W is cooled by an 11-blade 135mm fan that carries a Cooler Master logo. The actual maker is also indicated in small print. It is Young Lin Tech and the fan model is DFS132512M. Its specified speed is 1500 RPM.

The start speed of the fan is much lower than with the previous PSU at only 700 RPM. This is satisfactory even for very quiet PCs.

The fan begins to accelerate sooner, at a load of 600 watts, but does this less rapidly, reaching a peak speed of 1500 RPM at full load. Thus, the Silent Pro M2 1000W is quieter than its predecessor at any load and is generally very quiet for its class.

Efficiency and Power Factor

The Silent Pro M2 1000W is 88.9%, 89.4% and 85.5% efficient at the reference loads of 20%, 50% and 100%, respectively. It meets the 80 PLUS Silver requirements. Its peak efficiency of 90% can be observed at a load of 386 watts.

The power factor is about 97% at high loads, which is somewhat lower than what you normally expect from a PSU with active power factor correction.

Standby Source

The standby source does its job without a problem.


The Silent Pro M2 1000W is superior to its predecessor in the key electrical parameters: voltage stability and efficiency. It is also much quieter (even though the older model itself was only noisy at very high loads). These advantages justify the somewhat higher price and scantier accessories, although the Taicon capacitors raise our concerns anyway.

And make sure the selection of cables suits your configuration. Otherwise, you may have problems connecting your components to this PSU.


This comparison is a good illustration of the progress in the PSU field. The two models are comparable in price and formally identical in their output power (in total output power as well as in the load capacity of the particular power rails) but their practical performance differs dramatically.

The two-year gap between them does show up (well, the circuit design of the older model goes even further back into the past: the FSP Epsilon series was introduced in 2005 and its interior design hasn't been revised much since then). The newer model is more efficient, quieter and stable. Considering their comparable prices, the older model has no chance even with its better accessories. The vibration-absorbing pads can't make its voltages stable.

The Silent Pro M2 1000W can be recommended for top-end PC configurations even if you are fastidious about the noise factor. Unfortunately, its cable system is less handy than its predecessor’s. It is the only aspect where we see regress instead of progress between these two products.