9800GTX + mods = 800-900+mhz on water for core speeds...shaders are dependent on what overall load temps will be like...it is very common to see bench runs on vmod'd GTX's with shaders in the 2200mhz range...for folding use on water though you should be perfectly stable around the 1998-2052mhz range.
IMO, my GTX is water-cooled running below stock voltage at 800c/1998s/1175m for gaming use daily...folding at 790/2052/1150. pulls ~6.4k on the 700 point WU's and just over 7k on the 353's.
If you have a mobo you would like to mod..please, let me know. My solder station does not discriminate against PCB
You are pulling more than a stock GTX 285 in some situations!