I have the same motherboard, and since I dont know how good your ram is I can tell you a very good way to set your proc to give you another 200mhz and keep your ram running at 400mhz.
Go into bios:
Set ram divider to 133mhz and leave all else on the ram stock.
Set the HTT Multiplier to 4x
Go into the Jumper free config and set the HTT speed to 252mhz and change the CPU Multiplier to 9.5 and the voltage on the cpu to 1.35v (if that isnt stable raise it by one notch until you get stability, but shouldnt have to go above 1.375v at any rate)
Make sure the PCI-E is locked at 100mhz and that PCI is locked at 33.33mhz
This will make your system run at 2.4ghz, and you ram run at 400mhz!
This should help with you noticing a different, as far as tests go...you can run some 3Dmark programs or PCmark, which can be downloaded at www.futuremark.com or prime95 (for stability), mem test (for ram stability), HD Tune (benchmarking Hard Drive Utility and Monitor), and CPU-Z can show you your settings and system information for you!
Not sure if this will help, but it is an Idea!
P.S. You can get that CPU much higher, I used to run mine at 2.60ghz and was able to hit 2.8ghz, I was just showing you something simple and easy that shouldnt bother other components of your comp to much!
Best,
3Ball