Hi. I have got an ATi X1600 Pro 256MB and while im playing LFS it tends to drop from 80fps to like 12fps every few minutes and i dont know why it does it and it has only just recently started doing it and it cant be the graphics card because i have only recently got it and it plays all other games perfectly fine.

Check out the "minimum sleep" setting in LFS.

Wheres that?

Its on 1ms do i need to change it?

Yeah, try 2 or 3. I think I got mine on 3 and it's all smooth at >80fps at all times.

ok but mine drops from 80fps to 12fps then back to 80fps after about 5 seconds

If the minimum sleep thing doesn't help then check out this:
http://www.lfsforum.net/showthread.php?t=3105

Quote from xaotik :

http://www.lfsforum.net/showthread.php?t=3105

Originally Posted by Blowtuts from RSC Forums
I had this problem for a week or so. Bugged the hell out of me. Found a tip from someone on here to go to device manager, and update the driver for the 'computer' bit. right click on acpi etc etc, choose update driver, select driver from list, and choose advanced configuration and power interface (acpi) pc. I have no understanding of why this works, (considering both are the same name with a different way of saying it) but it did the trick for me.

Maybe it is easier