Here's what I've got to start with:
Asus P5WD2 Premium mobo
Intel Pentium D 830 Smithfield (3.0GHz)
2x1GB pqi DDR2-5400 RAM (4-4-4-12 timings)
eVGA 7600GT w/Zalman VF700-CU VGA cooler
Seagate 300GB SATAII
Zalman CNPS9500 CPU cooler
SoundBlaster XFi extrememusic
Antec TruPower 550W Power supply
CoolerMaster Cavalier tower
I'm running stable @3300 MHzright now, ~45-50 degrees idle, 55-60 degrees at load (audio encoding/mixing/sequencing). Can I squeeze 3.6GHz or 3.9GHz with this setup? I plan on replacing the RAM with OCZ or Crucial, maybe geting a second HD for RAID0.
What's your Vcore @ now? If you watercool it you should see at least 4.0Ghz (1.4Vcore) if not up to 4.5Ghz with your existing RAM and an even higher Vcore. You may even be able to push it higher but that is based on cooling solution and other variables. If your sticking with your current cooling solution, get some Arctic Silver 5 and with proper case air flow and increases in Vcore you may see 4.0+Ghz. Proceed slowly and monitor you temps closely. Good luck.
Ok, well you can raise it to 1.4(manually of course) and still be within max factory recommended Vcore and temps should still remain reasonable but I'm wondering why your Idle is what it is with the Zalman you've got. Try some AS5 as I posted and ensure you have adequate air flow through your case. If you noticed my sig. my 630 is @ 4.2Ghz watercooled. Not in my sig is it's 28-29c @ idle & 41-42c @ 100% load. It'll OC even higher but my memory is already OC'ed enough and I'll have to upgrade to DDR2 667. My CPU still has even more headroom and I suspect yours does as well even though it's dual core. You also have the best air cooled solution from zalman so hopefully AS5 will help.