Setup is:
i7 920 @ 4.2
Asus ENGTX 580
W7
Have windows 7 on a small 120 Gig SSD and am recording onto a 1TB HDD.
The HDD doesn't seem to be the bottle neck as I can record @ 60 fps till I run out of space.
But perhaps toggling record on and off messes with it. I dunno.
Any insight would be appreciated.