When it comes to testing a power supply, there are two courses to travel. One takes you down a path using a device to stress out the PSU and provide data regarding the power levels across all three rails. The second, and the one I make use of, utilizes an actual test system to give a more real-world account of what the power supply is capable of. While both methods have their merits, I prefer to use an actual computer to more closely resemble the manner of use that you, the potential customer, will put the product through.
That said, let's take a quick look at the test system. At the request of readers, I have beefed up the system to put a more realistic strain on the power supply.
Gigabyte 965P-DS4 motherboard (Supplied by GIGABYTE)
Intel Core 2 Duo E6600 processor
2x 1024MB Corsair XMS2-8500-C5 memory (Supplied by Corsair)
2x Sapphire X2900XT graphics (Supplied by Sapphire)
Western Digital 250GB SATA hard drive
2x Western Digital 160GB SATA hard drives
Western Digital 80GB hard drive
Sony 52x CD-ROM optical drive
Samsung 16x DVD-R optical drive
1x 200mm fan
2x 120mm fans
4x 80mm fans
While this isn't a Quad-GPU setup, we are certainly in the realm of having a system that is going to put a significant power drain on any power supply. The X2900XT graphics cards alone are going to be drawing close to 250 watts each when under load! Testing will consist of checking the power levels across all three rails at idle and again while the system is under stress. This should give us a good look at the capabilities of the power supply being tested.
This is out first test with the new dual X2900 series graphics boards and to see the Tuniq Ensemble handle it with no trouble was very nice. While we are not pulling the full 1200 watts of power, it is safe to say that most power rigs will not be pulling what our test rig does. If it can remain completely stable under these conditions, odds are good that it will handle your own rig with ease.
From the chart above you will see that we never dropped more than .02v during any phase of testing. Since I have a multimeter attached to the power supply, I can monitor it in a constant basis and I noted no fluctuations during testing. This PSU handled everything I could throw at it and never even blinked. Very nice indeed.