Otis, are you talking about the GPUGrid Preferences, Maximum CPU % for graphics setting?
If so that is for projects to use in rendering screensavers ... no one here would ever be running anything as a screensaver cause that takes away from crunching doesn't add to it right?

Mabyboi: the only increase I see on your card is that you upped the shaders from stock to 1584 and I don't think you are getting all you can at that speed. Not only is Win7 and HT being on slowing you down a bit but can you tell us what your CPU core speed is?

If everyone can add their OS to the info that would be great. While our CPUs are being used very little I think they are actually a bigger bottle neck than we could have possibly imaged. On one hand it makes no sense that something used so little would have much of an effect but I have seen a difference on gpu usage between HT on and HT off which equates to CPU availablility. I am trying to track down how much clock speeds themselves matter also. Think of it this way ... while the GPU is waiting for the CPU, it is doing exactly that ... waiting. As a reference to the numbers below the Vista64 machine is running at 4.2 GHz and the XPPro @ 4.0 GHz. I also used only TONI_CAPBIND wus in my analysis.

I use Precision and Voltage Tuner (both from EVGA)

GTX 295 (EVGA vanilla)
@1038 mv = 576/1242/999 (stock mv (1038) and stock frequencies)
@1038 mv = 576/1512/1080
@1075 mv = 576/1548/1080
@1088 mv = 576/1566/1080
@1188 mv = 540/1584/1080 (max volts from voltage tuner)
@1188 mv = 540/1656/1080 (max volts from voltage tuner)

My card can run these frequencies on both Vista Ultimate 64/ Win7 Home Premium 64, and XP Pro 32

WinXP gets better runtimes than Vista (and Win7) at SLOWER frequencies
Vista @ 1584 = 18425 seconds runtime (57424 ppd)
XPPro@ 1512 = 17725 seconds runtime (59693 ppd)

gets better as I bump up shaders on XPPro
XPPro@ 1656 = 16850 seconds runtime (62793 ppd)

The thing I can reason as to why they have such different runtimes is that Vista and XP have very different CPU runtimes for the same type WUs.
Vista 64 = 2700 seconds
XPPro32 = 850 seconds.

I now have my 295 runing on XP Pro 32 HT OFF and cpu dropped to 600 seconds, I'll have to wait a bit to see if my overall runtime drops.

Overclocking is nice and can get you better runtimes but I think OS is actually more important.

While you might think I am crazy take a look at the Top Hosts ... the only other two card system that beats me has 275s and I swear I'm gonna catch that one