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. I have continued to beef up the system to put a more realistic strain on the power supply.
MSI X48C Platinum motherboard (Supplied by MSI)
Intel Core 2 Duo E6600 processor
2x 1024MB Corsair XMS2-8500-C5 memory (Supplied by Corsair)
Sapphire X2900XT graphics board (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
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. Our testing of this power supply will be done with only a single video board since it is not designed for dual high-end graphics. 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.
For a lower tier product, I was expecting a bit more drop between idle and load, but the Rosewill RX630 did a decent job of keeping up with the power needs of the test system. Under load, the single graphics card used is capable of pulling close to 150 watts of power on its own, but the dip in power load was minimal even under those conditions. I did note a fluctuation under load of between .1 and .2 volts, but it was an occasional flutter and not a consistent jump between the range. The 5v rail fluctuated .001v under load, but this is not particularly unusual.
Some may note that the 12v rail seems to be rather underpowered, but the level falls well within even a stingy +/- 5% of the rail rating. Also keep in mind that most graphics card manufacturers recommend a power supply rated to at least 700-750 watts when using the 2900XT series boards, so a small hit in that rail wasn't really unexpected.
Overall, the numbers show that the Rosewill RX630 is capable of handling the load of systems up to a borderline enthusiast rig. Considering the graphics card used during testing, it would be safe to say that it can wear the "Xtreme" tag with confidence.