Can be done like this.
http://www.hardforum.com/showpost.php?p=1032821446&postcount=2
Setting the core affinity with NVIDIA GPU2 client (original by Sunin)
If you run a NVIDIA client with core version 1.07 or above (this can be found by looking at fahlog.txt, before a workunit start), you can configure the affinity precisely. This can often boost the performance, especially when you are trying to run multiple clients or you want to avoid using core 0 to reduce the graphics slowdown.
With core 1.07 or later, they introduced a new environment variable called NV_FAH_CPU_AFFINITY and it take a binary mask. A binary mask is just a programming trick to set the bits but for the majority, it may be a bit confusing so here is a full list to help you get the correct value :
Code: 0 = all cores
1 = core 0
2 = core 1
3 = core 0 + 1
4 = core 2
5 = core 0 + 2
6 = core 1 + 2
7 = core 0 + 1 + 2
8 = core 3
9 = core 0 + 3
10 = core 1 + 3
11 = core 0 + 1 + 3
12 = core 2 + 3
13 = core 0 + 2 + 3
14 = core 1 + 2 + 3
15 = core 0 + 1 + 2 + 3 Alternatively, there is also a simple way to determine the value :
Code: Core 0 = 1
Core 1 = 2
Core 2 = 4
Core 3 = 8
If you want core 1 and 3 only, add 2 and 8 to get 10.
If you want core 0, 2 and 3, add 1, 4 and 8 to get 13. For your information, if you have a quad-core, setting a value or 0 or 15 set the same affinity to all cores. If you have more than 4 cores, each additional core always take a 2^n value where n is the core number, starting from 0.
Now that you know how to determine the value to enter in the environment variable, we need to create that variable. Here is the simple steps (OS independent) :
-Go to start and run type in: sysdm.cpl then a system config panel should pop up.
-Under the Advanced tab click the environment variables button.
-Click new and under Variable name put NV_FAH_CPU_AFFINITY
-Under Variable value put the corresponding # you desire... Look above to determine the desired value.
-Walla, you have now setup the environmental variable hit Ok and close the window.
-Stop and restart the GPU2 client to make use of the new environment variable.
Your GPU should now utilize whatever cores you specified! I generally use 15 to allow it to use all cores. Then just check the box as indicated above in Xil's guide to not lock the GPU to a single core and your ready to roll!
Most I can get out of both of mine is 658 core 1703 shaders.
