Some general observations I've made while mining on Windows:
- Having MSI Afterburner open reduces the hashrate on my 5850s by about 10 MH/s.
- I have to set the affinity of Phoenix to a single core, usually the last one, otherwise the MH/s fluctuate significantly. In my case, this is the 4th core of my i5-750.
- The RPC CUDA miner will drop its hashrate if the console window hosting it loses focus. I was able to remedy this by setting the priority of the "rpcminer-cude.exe" process to "High".
I got annoyed at having to constantly set all this up every time I had to shut the miners down, so I'm in the process of writing an app to do it all for me, as well as monitor everything via HTTP:http://i55.tinypic.com/fbbady.png