Without further ado, lets get right down to testing. The graphics testbed used is almost similar to that on our GeForce 7950 GX2 article, but the difference is that we went with the ASUS A8N32-SLI (nForce4 SLI X16) motherboard. Equipped with the latest BIOS version (1205), we set out to setup the system with an Athlon 64 FX-55 processor and 1GB of low latency DDR400 Kingston HyperX memory. The change of motherboard has nothing to do with compatibility other than running tests concurrently with our usual MSI K8N Diamond Plus motherboard whose BIOS is also the latest version at 1.22, supporting the GeForce 7950 GX2 perfectly. You needn't trouble yourself with thoughts of performance discrepancies, as we have verified them and were too small to be of concern; they were perfectly comparable. We would have loved to have had plugged in a much faster processor to alleviate any CPU bottlenecks, but time isn't on our side and we do not have the luxury of holding on to these expensive toys for the rich. In any case, the FX-55 is hardly a slouch and higher resolution testing with greater image quality settings can quickly overwhelm any graphics card, thus testing the card's capability.
Of course besides the comparing with the GeForce 7950 GX2 itself, we had other graphics card configurations for comparison such as the following that lists all cards and the driver versions tested:-
Here then are the benchmarks we used to gather the performance results presented in this article:-
As mentioned in the preceding article, the GeForce 7950 GX2 draw up to 143 watts at peak operation. Now that we are SLI'ing the GeForce 7950 GX2, the max power draw shoots up to 286 watts. Of course you and I know that the secondary card is usually slightly less taxed and the real world use would probably meter the consumption at less than the peak values. At such high power consumption for a Quad SLI setup, we highly recommend nothing less than a 550W PSU to give yourself a safe overhead and perhaps some light expansion leeway.
Nevertheless, we did something a little out of the norm – perhaps even considered as suicidal. What we did was hook up the dual GeForce 7950 GX2 graphics cards in a system fit with the Athlon 64 FX-55 processor, two sticks of 512MB memory, dual hard drives, an optical drive and three fans (including the CPU cooler) to a .... 480W Antec power supply unit. Of course we had plenty of other higher performing power supply units (such as the 550W unit in our old AGP testbed), but you could say that we were just testing the tolerance.
To our amazement, the system worked great for the eternity of the two days we had been running benchmarks on the Quad SLI setup. If you did some math, our configuration was just bordering the maximum potential of the power supply unit, but somehow it pulled through fine. Given the average efficiency of power supply units, we highly advise against attempting this yourself and stick with nothing less than a good 550W power supply or better yet, opt for those 600W or even higher rated units depending on your system configuration to avoid facing any issues.