Performance Scaling with OCZ's 8800 GTX

Final Words

There really is quite a lot of data to chew through, but it is difficult to really draw solid conclusions from it. Let's start by summing up what we know.

First, core clock impacts performance very heavily in TES4: Oblivion and F.E.A.R. We know this because the percent performance improves at a given clock speed is the nearly identical to the percent clock speed increases. We also know that the same is not true for shader clock increases under both Oblivion and F.E.A.R.

We can speculate quite a bit about this, but we would need more information to take it very far. For instance, because core clock speed affects performance more than shader clock, we can assume that the functions controlled by core clock speed are more important to performance in these games than pure shader processing. Core clock controls the input assembler, vertex, geometry, and fragment thread scheduling, triangle setup, rasterization, texture address and filtering, and final pixel output through the ROP. At best, we can say that the games we tested benefit from improved performance of these subsystems more than improved pixel and vertex shader processing speed.

This begs the question, why do we see better performance from improvement of aspects other than pixel and vertex shader processing. The answer could be that the games we chose are heavily texture or fill rate limited, it could be that the overhead of DX9 requires more processing on the GPU outside the shader hardware and is preventing increases in shader clock speed from really mattering, or it might be that the hardware isn't able to schedule threads fast enough to keep the shader hardware busy.

If we are texture or fill rate limited, future games that make heavier use of SM3.0 and, further down the road, DX10, will start to see more of a benefit from improved shader clock speed. If DX9 overhead is getting in the way, we might only see shader clock matter under Vista. The worst case scenario would be if the hardware isn't able to keep the shaders scheduled without help. Of course, this is also the least likely case.

While clock scaling is fun and exciting to talk about, we do have the matter of our OCZ hardware to attend to. While there isn't anything special about it on the outside, we were able to achieve very good performance through a balance of memory and core overclocking. While we only tested one sample, OCZ's selling point seems to be their card's overclockability as enabled by their chip and memory module selection. If they are true to their word and we can expect similar performance from every part they sell, these parts could fit quite nicely into anyone's overclocking plans.

At the same time, it is tough to make a recommendation based on such an untested claim, especially when our only hardware came straight from OCZ. Time will have to tell whether or not OCZ's marketing does right by its customers, as we won't be going out and testing a random sample of retail OCZ 8800 GTX cards.

For those interested in overclocked parts, it is usually a better idea to go with factory modified hardware. The only clock speeds that are guaranteed to run are the ones you get out of the box. But for those willing to gamble, OCZ's entry into the 8800 arena looks at least as good as the other cards we've tested. In the least, our tests did not prove their marketing wrong.