We have to settle for real-world experiences. We took an NFORCE 590 SLI reference mainboard and equipped it with Conroe dual-core E6600 processor and overclocked it towards 3.4 GHz to make sure we are using more powah !

Now we equip this system with 2x GeForce 8800 GTX 768 MB, set up in SLI, 2 GB DDR2 memory @ 800 MHz, and an HDD. We now overclock the graphics cards at 625 MHz on the core and 2100 MHz for it's memory. Remember that we already overclocked the processor from 2400 MHz towards 3.4 GHz as well !

We loaded up SLI drivers, and enable a seriously funky gaming experience at a monitor resolution of 1920x1200 (a good balance between hefty GPU usage whilst using the CPU at maximum as well). Pretty spiffy stuff huh ?

Now for the test we looped test 2 (nature) of 3Dmark06 which is a total bitch on graphics cards, they make them sweat ! We set the resolution at 1920x1200 enabled 8xAA and 16xAF to make sure the graphics cards are being kicked in the nuts.

We run it three times and monitor the behaviour of the PSU with a wattage meter and multi-meter. The wattage meter will tell us how much peak wattage we were able to pull from this PC and the power-meter will tell us how much voltage is boosted though the voltage rails. Interestingly the results were 100% similar to the Tagan PSU we recently tested.

This PSU however is quieter and much cheaper !

LOW is the lowest measured value and HIGH of course the highest voltage peak we measured. A 5% fluctuation is perfectly acceptable, so 12 Volts should remain between 11.4 - 12.6v as you can see the PSU when stressed stays FAR from that.

So we took the primary voltages in both IDLE and LOAD (fully utilized) modes. We noted down the lowest and highest value we see and that is the fluctuation. If a PSU is unstable we'd see much fluctuation, differences and discrepancies which can result in system instability.

There's no such thing going on for the for the Dark Power PRO 850W. It is stable. During the load test several times I felt to see if the PSU was warm. Nope, it remained cold at all times. Really impressive as wattage peaked towards 500+ Watt many times.

It's really hard to stress PSU's like these. The fact that it remains stone cold at a 515 Watt power draw however tells me that it can easily cope with the load.

Now then, you've had a peek at the photo's, combined all factors, and now you should have a pretty broad idea of how this PSU would function for your current or future PC. Quite honestly, I did my best. In a 3D intensive test run with 100% utilization, in an overclocked environment this youngster is stable as can be. Remember this was tested on a NVIDIA GeForce 8800 GTX (overclocked) SLI system with an overclocked (+ 1000 MHz extra) E6600 Core 2 Duo processor.

Sound levels (dBA)

Well, the lack of it. As usual we grabbed our dBa meter, enabled the PSU by hot-wiring it and started to listen if it made any significant noise. Short and simple it's silent, yet the fan in the PSU made a slight weird noise. Not at all irritating, but it probably was slightly damaged somehow. But even then we measured a nice level below 40 dBA.

The human hearing system has different sensitivities at different frequencies. This means that the perception of noise is not at all equal at every frequency. Noise with significant measured levels (in dB) at high or low frequencies will not be as annoying as it would be when its energy is concentrated in the middle frequencies. In other words, the measured noise levels in dB will not reflect the actual human perception of the loudness of the noise. That's why we measure the dBa level. A specific circuit is added to the sound level meter to correct its reading in regard to this concept. This reading is the noise level in dBA. The letter A is added to indicate the correction that was made in the measurement.

All in all, very silent and thus highly recommended to any of the audiophiles that like silence (yours truly included). As always we measure 75 CM away from the product (usually the distance between you and a desktop computer), and yes .. this test is always a tad subjective.