FAN Reference?

Ok so I ran Orthos overnight for about 6-7 hrs. temp averaged around 54 C. So the next step I guess is the replace the stock FAN.

Pentium D 820 and ASROCKS 775i65G board. Now I've a dozen fan reviews, but do all fans fit all boards?

What would you suggest for this combo?

Any heatsink with s775 mounting kit should be able to fit that motherboard. How much money are you lookin' to spend? Personally, I'd go with one of the Thermaltake Ultra series.