graphic clock & processor clock

When I look at the specification of GT 220, there are two clock rates: graphic clock(625MHz) and processor clock (1365MHz), it has 48 cores.
I am using CUDA for scientific computing and I want to fingure out the potential computing ability, which clock rate should I use? What’s the other clock rate for? Thank you.

To confuse things even further, there is a third clock for the memory controller. But to answer your question, you should use the processor clock. The graphic clock domain covers a lot of the fixed function graphics pipeline hardware and miscellaneous stuff.

Are you talking about the memory clock?