Well, colour me ashamed of my n00b error...! It was something which crossed my mind a week or two ago, but I dismissed on the basis that everything else *seems* to run fine, and I assumed (without checking, bad move!) that both my PCI-e x16 slots run at x16. They don't. One runs at x4. My graphics card was in the slow one. I usually have 5 hard disks plus an e-SATA connector plugged into the mobo and the connectors face upwards (not at 90° as you see on new boards), so I can only use four of six SATA connectors when the graphics card is in the x16 slot. I've pulled out 2 disks and now I have doubled framerates in F1 2011. Oddly enough, it doesn't seem to have improved Rift by more than about 5-10 FPS and other games not as dramatically as F1. But a huge improvement in F1 2011. Phew! I still get stuttering (replay file issue), but not as badly as before. I think its now more a case of 'I know what I am looking for' than it being a major problem. I'm hugely relieved (and a little bit ashamed that it didn't click sooner). I'm much less peeved with Codies now, although still a bit grumpy that the save-game gremlins and stuttering from 2010 still exist in 2011.