@EllisDJ
http://www.xtremesystems.org/forums/showthread.php?257528-MSI-GTX480-review-with-CPU-scaling
980X @ 3.3 and 5.0 using a single GTX480, both stock and OC'd (so close to 580 speeds).
Notice how the CPU OC (red vs green bars) does practically
nothing.
The only game that gets any real benefit is FSX, which is a notoriously CPU bound game. The rest, 2fps if you're lucky from your 1.7GHz OC.
As for BC2, it's a very optimised game for multi core, and you really shouldn't have been having slowdown with a 3.8 Q9550. I've got a 3.9 965BE and it's smooth as a baby's buttocks with a 560Ti @ 1080p 4xAA 16xAnniso...
As you can see the difference between ~3.2-3.7 isn't massive. And that is only using 2xAA and 4xAnniso. Had they used the more common 4xAA and 16xAnniso the difference would have been practically non-existent.
http://www.techspot.com/article/255-battlefield-bad-company2-performance/page7.html