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Review of Be Quiet!'s Dark Power Pro 10 vs. Power Cool X-Viper

In this review I will be looking at two 850w power supplies, one from the well-known company Be Quiet! and the other being the less well-known Power Cool. I will be comparing features to see how stable they are powering 2 x 680s in SLi and also just how quiet they are when under a heavy load.

In this review I will be looking at two 850w power supplies, one from the well-known company Be Quiet! and the other being the less well-known Power Cool. I will be comparing features to see how stable they are powering 2 x 680s in SLi and also just how quiet they are when under a heavy load.

Be Quiet! Vs. Power Cool BoxesBe Quiet! Vs. Power Cool Boxes

Both of the power supplies are of modular configuration which I have found in recent years is a must when building computers as you can save space and will also assist with airflow through the case without those un-necessary power supply cables. In the past modular power supplies have been a lot less power efficient and it was the main reason not to buy them but in recent years, as can be seen with the Dark Power Pro 10, modular power supplies are just as efficient, yet more expensive.

Be Quiet! Dark Power Pro 10

First up is the Be Quiet! Dark Power Pro 10. Be Quiet! have always been a massive name in silent computer solutions making products such as cases and heat sinks, but in more recent years they have also made advances into the PSU market as well. For me this makes sense as power supplies can be very noisy under load and since you cannot change the cooler like you can on graphics cards or CPUs it made sense for Be Quiet! to make a near silent power supply for those people that like their peace and quiet when gaming.

Be Quiet! list the following features on the box:

  • Virtually silent operation achieved through a broad array of meticulous optimizations, including use of Be Quiet!’s custom-designed 135mm SilentWings® fan;
  • SilentWings fan features airflow-optimized fan blades, fluid dynamic bearing with copper core and high quality IC motor controller for the quietest possible operation;
  • 80PLUS Platinum certification  and up to 94% power conversion efficiency let you do more work with the same power and reduce your power bills;
  • 850 Watts of continuous power provide deep power reserves for demanding computing applications;
  • NVidia SLI and AMD CrossfireX multi-GPU certifications allow you to build intense Quad-GPU systems with absolute confidence;
  • Cable management with extra-long cable reach simplifies component installation and reduces annoying clutter, increases airflow and improves cooling in even the largest PC cases;
  • Overclocking key allows switchover between quadruple independent +12V rail mode and high-performance single-rail operation;
  • German product conception, design and quality control.

As you can see from the above list Be Quiet! have gone all out to ensure that not only their power supplies are quiet but also that they appeal to gamers and power conscious people by stating that the power supply has a very impressive 80plus platinum certification giving it a 94% efficiency, as well as stating that it supports multiple graphics cards.

Be Quiet! boxed-upBe Quiet! boxed-up




As you can see from the above picture the Dark Power is shipped in a rather large box, and on first observation I thought there would be no reason for this, that was until I opened it up and saw just how many cables you get with the power supply, it could power a very large system indeed.

Be Quiet! in-box viewBe Quiet! in-box view








As you can see the box is very professionally done, very neat and tidy; I do like a well presented component and Be Quiet! always does a great job with their box products and the presentation is flawless!


Be Quiet! FanBe Quiet! Fan

Be Quiet! OutputsBe Quiet! Outputs







The unit itself is quite a heavy weight at 4.08kg (without any attached modular cables) but looks stunning and oozes the quality that can always be found with Be Quiet! products. As you can see the output sockets are very well and neatly laid out but I do rather like colour coding with the sockets to ensure that inserting the cables are fool proof. I should note however that you cannot insert the wrong cable into the wrong output, but it’s always good to have a belts and braces approach to these things.

Power Cool X-Viper

Next is the less well known X-Viper which is also a massive 850w power supply and is also modular. The X-Viper only comes with an 80plus bronze certification which is not fantastic when you look at other manufacturers in the market but at £59.34 from CCL you can sort of forgive the X-Viper for being a less efficient PSU.

Power Cool list the following features on the box:

  • Support - Compliance with newest Intel standards ATX 12V, V2.2, V2.91, EPS12V;
  • Efficiency - 85% at typical;
  • MTBF > 100,000 hrs;
  • Cooling System - Smart brand new 140cm Fluid Dynamic Bearing (FDB) Fan with intelligent Fan Control (800RPM ~1500RPM);
  • Protection - Over Voltage Protection (OVP), Under Voltage Protection (UVP), Over Power Protection (OPP), Over Temperature Protection (OTP) & Short Circuit Protection (SCP);
  • NVIDIA SLi ready.

Power Cool BoxedPower Cool Boxed

As you can see in the above picture the X-Viper comes in a box which is a lot smaller than the Be Quiet! one; I have to say it is one of the smallest boxes that I have seen for a power supply  - I also don’t like the design, but don’t let this put you off as the box you will only see once or twice (if you sell it on) I just like a well-designed box.


Power Cool Boxed-up ViewPower Cool Boxed-up View


As can be seen the box is not that well-padded when compared to the Be Quiet! and there also seems to be less power cables for the PSU when compared. As I have said above I’m very much a stickler for well-presented products.




Power Cool FansPower Cool Fans

Power Cool OutputsPower Cool Outputs








The unit itself doesn’t look bad at all I like a black finish on a power supply as I can remember when no effort was put into power supply designs and everything was just bare steal with no imagination but into them at all, how times have changed!

There is some colour coding with the power supply but not much. Both the PCIe connectors have blue output connectors to ensure that you do no attach the wrong connectors I do like the way that manufactures like Corsair colour code all their outputs.

Comparison and Tests

First comparison I would like to make is the difference in power efficiency between the 2 units. The Dark Power has a fantastic Platinum Plus rating and the X-Viper only has an efficiency rating of Bronze. To put this into real term ratings you are looking at a 94% (Max) efficiency with the Be Quiet!! and only a maximum efficiency rating of 85% with the Viper X; in other words the Dark Power Pro could give quite a saving over a year.

The fan’s sizes differ by just 5mm with the X-Viper being a little bigger in size. The X-Viper being a total of 140mm in size and the Dark pro being a little smaller at 135mm, it is going to be interesting to see how they both perform in sound testing under load and idling to see if the size of that fan will make any difference at all.



Dark Power Vs X-ViperDark Power Vs X-Viper

Since I don’t have the facilities to test the actual power output of both units I can only go on how I found the unit during testing on my test rig which features the below specs:

  • Intel Core i7-3930K 3.20GHz (Sandybridge-E) Socket LGA2011 Processor;
  • OCZ RevoDrive3 120GB PCI-E SSD;
  • Asus P9X79 WS Intel X79 (Socket 2011) DDR3 Motherboard;
  • Corsair Vengeance Blue 16GB (4x4GB) DDR3 PC3-12800C9 1600MHz Dual/Quad Channel Kit;
  • Asus Xonar D2X 7.1 PCI-E Sound Card;
  • 4x Seagate Barracuda 2TB 7200RPM SATA 6Gb/s 64MB Cache;

So as you can see from the above system specs there was going to be no taking it easy with regards to testing these units to the limit and beyond.

Both of the units worked in both single and dual card configurations and also powered the watercooling as well. I was surprised that the X-Viper kept my system stable and worked without any issues as with a quick search around the internet I found plenty of people not liking earlier versions of Power Cool’s power supplies.


I had a quick 2 hours each playing a few of my favour games including Crysis 3, L4D2, Bioshock Infinite and Anno 2070. I found that both of the power supplies were stable enough for the two hours gaming and some surfing afterwards.

The Be Quiet! was superb at what they do best, which is quiet components even under high load the Dark Power was virtually silent, I couldn’t hear a thing coming from it.  If you want a really quiet system I could not recommend the Be Quiet! Dark Power Pro enough. On the other side of the scale is the X-Viper which even when idle I could hear very clearly; surprisingly even when not using the computer I could hear the fan from the X-Viper.  It was even worse during gaming, even though it was stable, I could not get over just how loud the X-Viper is while under load, and I was just glad to get my headphones on and game without having to hear the fans whirring away.

I also found that the X-Viper created a lot of heat as well during testing, I couldn’t touch the PSU after gaming it was that hot which to me signals that I was putting the X-Viper under a lot of strain during testing and that it was close to the edge; any more load would have made the power supply unstable.

In contrast the  Dark Power Pro, even though it produced a bit of heat, was  practically silent but I think that Be Quiet! have put somewhat of an emphasis on being quiet over running hot, which I can really understand as that is what they are all about and time and time again they never fail to deliver.


In conclusion I highly recommend the Be Quiet! power supply. They are of a high quality of build with a great reputation and customer service policy. If I was building again for my system I think I’d go with a higher wattage rated version of the Dark Power Pro 10, for example, maybe the 1000w or 1200w version which I have heard preforms just as well as the 850w.

On the other hand Power Cool have a long, LONG way to go for any recommendation from me; even though they are a lot cheaper than the Be Quiet! alternative. The X-Viper being £59.34 Inc. VAT and the Dark Power being £191.46 Inc. VAT I can understand why you may consider the X-Viper but I would implore you to stop and think about what your PSU does for you!

Your PSU is an essential part of your system, a part which you should ensure is the best you can possibly afford as if it goes bang it can take other parts of your system with it, such as the motherboard or processor and this is why I warn you not to go cheap.  It’s also why I cannot recommend anyone to buy the Power Cool X-Viper, it’s hot, noisy, and dangerously close to the edge with my system.