Power Supplies by geoffrey @ 2011-03-14
Have you just put together your brand new gaming monster but are you still missing the equivalent strong power supply to match it. In this article we're putting the Coolermaster Silent Pro Gold 700W power supply unit against Corsairs Professional Series Gold AX750. Two quality build 80+ Gold power supplies in the ~700W market segment, did we get double Gold?
The first 80+ Gold power supply units have been around for a while now and more 80+ Gold models are being added each month so it seems. As the market slowly is being filled up with new gear we noticed that these top notch Gold rated units have now reached new territory: the 700 Watt market share. It still is the high-end equipment which many of you probable can only dream off, however if you’re the very power demanding kind of person then these products might be of some interest to you. The truth is that you’ll quickly be spending 120~150 Euros or an equivalent amount of dollars on one of these 700W units, money which could also be spend buying an 800~900W power supply as well. The thing is that for anyone with an overclocked air/watercooled computer using a dual/quad or even hexa-core cpu with SLI/CrossFire video cards, the 700W will cut if for you, it’s only for the very few which run quadSli/Cf and Prometeia cooled quadcores which might be really needing the higher wattage rated models. In return for choosing the 700W Gold units you mostly get higher build quality and guaranteed higher efficiency which translates into lower electricity bills. Interesting? Ok then, let’s have a quick look at both of today’s competitors.
CoolerMaster Silent Pro Gold 700W
Ranging from the ever-efficient 600W all the way up to the 1200W power supply, the Silent Pro Gold line meets the 80Plus Gold Standard. And to achieve this goal, Cooler Master incorporates three visionary patents into this innovative design. The Hybrid Transformer incorporates the transformer with the heat sink, not only reducing the size by 25% over traditional transformers, but by keenly conducting heat and increasing efficiency. The Heat Transfer Technology crafted especially for powerful, demanding power units utilizes and L-shaped design to ingeniously route air flow by the heat sink, resulting in greater heat dissipation and therefore providing an optimal performance. The Hyper Path adeptly places the integrated circuits tightly to the transformers, shortening the path and creating a more direct energy channel, reducing the energy loss to nearly nothing.
Corsair Professional Series Gold AX750
The Corsair AX750's energy-efficient design allows it to operate reliably with minimal cooling, and hence very low noise levels. The AX750's Hybrid Silent Fan Control technology offers three modes of cooling, depending on the load level. This includes a fanless mode of operation (0 rpm) up to about 20% load, a quiet, low fan speed cooling mode for typical loads up to around 50% load, and a higher performance cooling mode for more demanding loads. Corsair bundles this element with more traditional features like integrated active PFC with PWN controller, a large cooling fan, and a powerful single 12V rail in order to engage maximum performance.
Enough electrical mumble jumble for now, let's first give the product box some attention and see if there are any goodies to find in there.
The power supply comes in a gold colored box with on front the 80+ Gold label in big just to make sure you didn't look over it. More labels like 5 years warranty and NVIDIA SLI Ready are found on both sides as well, the back side of the box is covered with specs and some info the patented technology that is being used.
- AC power cord
- DC power cords
- User Manual
- Coolermaster Silent Pro Gold 700W power supply
- Cable bag
- 4 x mounting screws
Close-up shots
The SPG 700W comes in a dark grey color and measures roughly 150x160x86 mm. The power supply is of the modular type with the 24-pin ATX cable, 2x4pin EPS cable and 8pin PCIe cable hooked up internal. For cooling the internals Coolermaster uses a Young Lin Tech DC 12V fan, model DFB122512M. It's a 120mm fan which produces 70~85 CFM at 2000rpm ie. when the duty cycle is at 100%. PWM is normally supported by this fan, Coolermaster however doesn't use, it alters the fan voltage whenever more or less cooling is required.
Inside view
The inside view shows us a quite complex PSU design. The high side uses 2 x Matsushita Panasonic 270uF 420V elco's where a combination of dry and wet capacitors is found on the low side of the psu. To increase efficiency Coolermaster uses what they call Hyper Path. With this technology the high side switching transistor is directly connected to the main transformer, this reduces energy loss. Transistor used is made by Infineon, the 041N04N model is a N-channel MOSFET good for 80A, you get 2 of these.
They've also added heatsink cooling to the main transformer and this to further stretch the efficiency of it to the maximum. The patented L-shaped heatsinks are also found on other components and take away most of the daylight. You may also spot multiple upwards pcb's where low side rectifying and filtering is being done.
Corsairs box focusses on the multiple modular plugs that are found on this PSU. Furthermore you can find the 7-years warranty logo and small 80+ Gold logo on the side and specs+info on the back side.
Inside the box
- AC power cord
- DC power cords
- User Manual
- Corsair Professional Series Gold AX750 power supply
- Cable bag
- Power supply bag
- Tie-wraps
- 4 x mounting thumbscrews
Close-up shots
Corsairs AX750 is dark grey/black color and measures 150x160x86mm. It also comes with a modular design but with none of the cables internally vastened. External design of both Corsair AX750 and Coolermasters SPG700 is kinda likewise, except for the black fan mesh maybe. For cooling, Corsair uses a Sanyo Denki San Ace 120 9S1212F404 12V fan which is also used in other AX series PSU's. This fan is able to push roughly 70CFM at 2200rpm.
Inside view
Internally the AX750 differs greatly from the CM SPG700. High side filtering is being done with Nippon Chemi-Con 390uF and 330uF capacitors where the low side filtering is being done by a combination of traditional elco's and smaller aluminum capacitors. As you probable could have seen already there is only a minimal amount of heatsinks added, some of these go directly to the printed circuit board. Much of the low isde filtering and switching is done on a vertical PCB right next to the modular pluggs.
The following few pages we'll be focusing on what both PSU's have or have not in common. We'll be checking out the connectivity, efficiency and see how the PSU's handles a real-life load, but before we do that let us first compare the specifications...
Specifications compared
Both power supplies come with a single 12v rail design which in both occasions can put out around 60 Amps. The Corsair AX750 allows for the most output power, mostly because it comes with a tad stronger 12V line. Coolermaster's unit on its turn can have the most combined 3.3 & 5V power, on a relative perspective I guess it's safe to say both PSU's or made for the same purpose, if that extra 50W continuous power is of your concern then maybe you wanna look out for something stronger just to have that little more headroom.
Cables Explored
Left: Coolermaster SPG700 modular cables, right: Corsair AX750 modular cables
Compared with CM's SPG700 the Corsair unit comes quite some more modular cables, atleast that's how it seems on first sight: don't forget that CM's PSU comes with some connectors already hard connected to the PSU.
Main connectors like 24 pin ATX support, 4+4 CPU power plug and 6+2 PCIe power connectors are found for both models, and connectivity isn't scarce for either of them. The 4x molex connectors with Coolermasters PSU's is a bit on the low side for a high end device, floppy and SATA connectivity is good though. The Corsair AX750 offers the most connectivity of the two, with 12x SATA, 8x Molex and even 2x Floppy you're actually having it quite luxurious.
When comparing the length of the modular cables we notice the biggest differences between PCIe, molex, floppy and SATA cables. Where Coolermaster comes with the longest PCIe cables, Corsair makes it possible to even hook up SATA/Floppy/other peripheral hardware that might not even be inside your housing, some of their wires measure nearly one meter long!
Let's move on to electrical testing these units.
To put these pc power supplies to a test we used the Coolermaster PSU test-lab in Venlo (NL), for more info about the test setup I'll link you to a previous article where we made some in-depth PSU tests using the same equipment. Although we did add one of CoolerMaster's own PC power supplies in this article you must know at all times that we did our tests on our own according to our specs and requirements with little or no help from CoolerMaster supervisor René. Our result are not biased, our goal is to give facts, not to make advertisements.
Apart from using these industrial test devices we also made a real-life test using a self-build high-end pc where we also monitor the temperature & noise levels. More info later, on to our testing candidates ->
Using the Chroma electronic load we set the current draw so that we got 20, 50 and 100% load condition. Our results:
Coolermasters unit completely made it through the safety tests:
- Inrush current: 50,7 Ampére
- Power Factor: 0,88~0,95
- Standby power consumption: 1,07 Watt
- 12V shortcut protection: OK
- 5V shortcut protection: OK
We repeated these tests for the Corsair AX750 unit:
Safety tests:
- Inrush current: 40,9 Ampére
- Power Factor: 0,89~0,98
- Standby power consumption: 1,00 Watt
- 12V shortcut protection: OK
- 5V shortcut protection: OK
The AX750 also produces some top notch efficiency results. Protection circuitry works like a charm and inrush current remained surprisingly low at only 41 Amps. The standby power consumption (100mA load) is fairly good and so are the peak to peak noise levels found on each volt rail. Ripple is at only 10~15mV during heavy load, compare this with Coolermaster PSU and you know this is a superb score.
Let's put both PSU's head to head now ->
Efficiency is fabulous for both units, averaging at roughly 90 going from 20% to 100% load is quite some performance, hence the 80+ Gold label.
Inrush current in some way determine the life-time of some of the components, the lower the better. Both PSU's score well at 100% load but it is the Corsair unit which really takes the lead here scoring only 41 Amps, that's comparable to that of 500W units or even lower rated power supplies
Standby power consumption is right where you'd expect it, at 100mA load (5Vsb) both units break even at roughly 1W power usage. In 2012 new European regulation require the power supply standby power to be below 0,5W. To test the PSU for this regulation we had to remove the 100mA load at 5Vsb, that's all. As you can see, neither of the these units are having trouble here:
4 years after the regulation is in force (December 2012):
- Power consumption in off mode must be 0.5 Watts or less;
- Power consumption in stand by mode which allows reactivation must be 0.5 Watts or less;
- Power consumption in stand by mode which allows reactivation and displays information (such as a clock) must be 1 Watt or less.
Temperature & noise levels
In order to measure temperature and noise levels we had to make a self-build pc where we can eliminate pc noise and reduce ambient noise levels. Our test setup:
- CPU: Intel Q975 @ 3.4GHz 1,6V
- Mainboard: Gigabyte GA - EP45 - UD3P
- Memory: 2x1Gb TEAMGROUP Xtreem 800MHz 4-4-4-10-35-4-10-10-10-2T @ 800MHz
- Graphics: ATI Radeon 4870X2
Noise wise we have two good performers on our hands. It must be said that it was kinda a frightening sight to see the Corsair PSU fan not spinning upon first powering it on, not having the time to look at the specs it thought it was DOA before actually putting it to test. Silly me it was only the fan which is being put off by the PSU itself when little power is required by the PC. Therefore it is normal for the Corsair unit to score really well at idle status. But even with the machine running heavy benchmarks the PSU noise didn't climb too high in noise level. At full load, Coolermasters Silent Pro Gold 700 scores a little worse with the PSU being slightly higher audible (only if no other sound is apparent), but the noise level is actually still quite good.
PSU input temperature was measured usign a Velleman DVM345DI digital multimeter. Output temperature is monitored using a Greisinger GTH 175/Pt digital temperature probe. Room temperature is at roughly 20° and the PSU-in air temperature is roughly 30~33°C idle and 37~40°C at load.
In this article we've been comparing two top notch products both capable of producing up to 700~750 Watt quality power for your PC. Efficiency in between 20 and 100% load is guaranteed to be at least 80+ Gold, in our test we saw average efficiency of around 90%! At high loads output voltage is stable and well within ATX specifications while the sound noise level remains relatively silent.
When we look more into detail we do notice some differences between the two competitors. In both connectivity and cable length the Corsair AX750 is a bit more luxurious than the Coolermaster Silent Pro Gold 700. The latter comes with only 4 molex connectors to connect your peripherals with, and while molex is less used now with SATA being more of a standard, 4 connectors is not a lot much for a high-end product. Remember these PSU's are modular so if the user doesn't need them they could easily put it out of their way by just disconnecting the modular power cord. High-end users tend to be very creative with hooking up all kinds of periphery... Aside of this we also found the Corsair unit to produce less AC output ripple, less AC inrush current and little less sound noise. In contrary, Coolermaster's Silent Pro Gold offers little extra cooling power for your PC internals.
Standby power consumption is good and conform with new EU2012 standby power regulations for both units. In order to maintain a good power factor, Active PFC is being used and this seems to work quite well, only at low load levels it gets harder for both units to stay near the perfect PF of '1'. Safety wise they both did survive our short circuit test, if however you're being given the very special talent to kill your computer hardware in a very short period of time, do know Coolermaster gives a warranty period of 5 years where Corsair even extends this up to 7 years! Some trust they have...
At the time of writing we found the Corsair Professional Series Gold AX750 to be priced €138 where the Coolermaster Silent Pro Gold 700W goes for €110. At these price rating you'll probable find higher rated products but do know they come with lower efficiency and probable are less silent too. At €138 the AX750 might be a little overpriced compared with Coolermaster's unit, but in return you do get more luxury and little less extra performance on a electrical point of view.
Before I let you go I'd like to thank Coolermaster for having us over once again and for supplying us their review sample, I'd also like to thank Corsair for sending us their reviewing sample of the AX750 power supply. I hope you liked reading this article, until next time!