There is another overlooked setting that influences temperature : hyper-threading.
I've got quite a "stock" system : Core i7 920, on an ASUS P6T Deluxe V2, everything running at stock speed, stock cooler, typical 6-fan case (case is closed btw), about 21 room temp. Actually, the only thing not at stock setting is memory : upped voltage to 1.64V to run 3x2048MB DDR3 1600MHz DIMMs at 1066MHz but with lower latency (5-5-5-12).
Running prime95 torture test ("In place large FFTs", the worst on temperature, 8 worker threads) brings CPU temp to about 80 and individual Core remain within 84-87 after 30 minutes, while the CPU fan is partying at 2200 RPM. Stock cooling is definitely not good for heavy number crunching.
BUT... if I disable Hyper-Threading from the BIOS and run the same test (4 or 8 worker threads, doesn't make any difference), CPU temp stays around 71, while individual cores stays within 75-79 (still within 30 minutes or so, I haven't seen any difference from 10 to 30 minutes anyway)
Therefore, it seems you can get you CPU 5-10 degrees cooler just by disabling HT. Personally, I have yet to experience any human-noticeable performance drop after disabling HT, even on hardcore Photoshop CS4 batch processing (lots of filters, not too much disk access)
My advice : check with your most demanding "real uses" if HT makes any difference. If it doesn't, keep it disabled. If it does, you might want a better cooling solution.