Thanks for the reply guys. I'll try to answer everyone:
@RobertN: No overclocking done at all so far. Its a brand new system all new components running at stock.
@Buckster: Yes pretty sure its the rght slot. It's in the top slot which is a dedicated x16 pcie slot. Its the one they recommend int he manual for best performance.
@Marvin: Yes the CPU and GPU fans are going strong. I've re-seated the CPU and made sure its sitting right. No idea about motherboard features though. In the bios theres some fan control/monitor features bt I haven't touched them.
@Buckster: What is CPU throttling and why would it be happening?

I've checked the CPU and mobo temps and they're fine. Very stable with nothing over 40' other than the Northbridge which is at 45'.
@Muel: As mentioned the temps seem fine. The system in general doesn't seem stressed at all other than the rubbish performance. Haven't tried memtest yet but will do.
@mame: I installed realtemp but I get an error when i run it saying it doesn't support my processor...
Something I have noticed is this problem spreads futher than just during gaming. I tried a few videos, avi files and even YouTube vids are very choppy and have poor framerates. Even doing general stuff like scrolling up and down a web page can be laggy.
I just installed Dragon Age as a test of an offline game. Only having tried lotro and SC2 before. Dragon Age was terrible. The cut-scenes were down to 1 or 2 fps. The actual gameplay was just as bad. I even tried taking the settings right down to lowest but it was the same.
Dont know if it helps but I've uploaded some CPU-Z screens: