Be Quiet! Dark Power Pro 11 - 850 Watt PSU Review

PSU - Power Supply Units 107 Page 6 of 8 Published by


Load Testing The PSU

Load Testing The PSU

Testing a power supply these days is always a bit of a challenge at hand. I mean without professional load testers it's pretty hard to stress a power supply of this class and actually measure its behavior.


Our first check is with a simple cheapo power supply tester, we monitor voltages quickly and check if all rails are working properly and within spec.

The Test Setup

So for our load test here's what we did. We emulate real world usage in this stage. We take an old energy hungry Intel P55 based Quad SLI compatible motherboard, armed it with them nice and ancient GeForce GTX 590 cards (each card has two GPUs). We combined the P55 motherboard with a Core i7 870 processor overclocked to 3.8 GHz. This old hardware will drain the system alright. The system... well have a look:

These are the components used:

  • P55 SLI motherboard (has high power consumption and an NF200 chip)
  • Core i7 870 (overclocked to 3800 GHz) 20x190 BLCK at 1.4 Volts
  • 1x GeForce GTX 590 primary (2 GPUs)
  • 4 GB Memory DDR3 @ 1520 MHz
  • OCZ Vertex 2 SDD x1
Let me clearly state that we use such a dated system so we can consume a lot of power.

Now, with a setup like this, a couple of years ago we'd have reached 500~550 Watts power consumption as maximum with just one graphics card. But with power supplies getting so incredibly efficient these days, even that proves to be a very hard task to accomplish. Now on the software side of things it is time to give the PC a decent beating. Remember our focus remains on PSU efficiency, not the components we use. We now take some other power supplies and start testing with one GeForce GTX 590 first: 


Looking at efficiency is actually a simple thing to do. We look at the powered off status, Windows IDLE status, productivity mode (we stress the CPUs) and during gaming. The lower the Wattage, the more efficient. The IDLE power consumption is average to normal. Above the worst and the best PSU we tested versus today's tested PSU, the lower the line the better.


Above a very simple test, once we power down the PC can still consume power. Following EU legislation your PC and thus PSU and motherboard combo needs to remain under 0.5 Watt in sleep or power down mode. 


For the following step we measure the PC power consumption in IDLE. Mind you this system is DATED. Current PC's all hover in the 50 to 100 Watt range when in IDLE. We notice that the DPP 11 850 Watt is doing really well, only 2 Watts away from the Titanium power supply actually, but most PSUs do quite well at this level.


When we focus solely on CPU productivity mode load for a second we see that the PSU draws 265W from the wall socket. CPU productivity is video-transcoding, content creation etc, your processors logical cores are 100% at work while your graphics card sips a Martini. As you can see, the efficiency is smack down in the upper class of efficiency -- that is really spot on.


Probably the best indicator for the Guru3D community is seeking a good efficient power consumption is by looking at the game test. As you can see the that the PSU draws 456 W from the wall socket. At 50% load a PSU is usually the most efficient so this one is doing pretty OK. The efficiency values even slightly below 50% load actually remains roughly at Platinum level efficiency albeit offering best in class numbers. 

Share this content
Twitter Facebook Reddit WhatsApp Email Print