Each card poses an interesting question. The NX7900GT and EN7900GS TOP come pre-overclocked, so it's a bit of a crapshoot figuring out how much further they can be pushed. The EN7950GT already led the other two cards at default speeds. Here in the HH labs, we won't stop until the silicon faulters, so we installed Coolbits and started raising those speeds until we began to see artifacts in the graphics. We then backed off a few MHz until fully stable, and re-ran a couple of benchmarks at each card's higher clock and memory speeds.
Each card comes with the same core, the G71, basically utilizing the same cooling mechanism which is anything but fancy. That being said, MSI's NX7900GT prominently promotes overclocking on their package and sports a slightly larger heatsink than the Asus models, covering the RAM as well as the GPU. It seems that MSI may have reached close to the maximum stable speed available with their card as we were only able to squeeze an extra 13MHz on the core and 35MHz for the memory. As expected, these minimal speed raises resulted in minimal performance increases. The seemingly lesser cooling on the Asus cards didn't deter us from gaining 40/55MHz on the EN7900GS and 44/97MHz with the EN7950GT. Gains were a bit more noticeable, with the 7950 GT nearly reaching the 5000 plateau in 3DMark06.