Odd 5970 problem

[breezy]

I've had the 5970 for a while now, and have been generally very pleased.

One issue puzzles me, however: Sometimes when I play older games they run at very fast fps for up to 15-20 minutes and then nosedive (I would estmate under 10 fps). The drop in fps persists even when I close and restart the game; I have to re-boot to get the fps back up to where they were before. I first noticed this issue with FEAR, and it just popped up again when I was experimenting with Tomb Raider: Underworld.

Strange thing is - it's never happened with a current gen game, only with games that are a few years old.

Eyefintity isn't the issue - the problem with FEAR happened before I got my extra monitors. Heat is also not the problem.

Does anyone have any ideas?

[Gilly]

What are the temps? You say there are not a problem but don't provide figures.

What are the other components in the computer?

More importantly... what is the PSU you are using?

What driver version are you using?

[breezy]

I checked the temps right after I exited TR:UW and they were at 77 C on both GPUs.

The PSU is low (a Dell 525W) and apparently not replaceable, but I haven't had any issues with it whatesoever - for ex: I played Metro 2033 with almost everything maxed at 3480x800 for at least 6 hours one night without a single hitch. I really don't believe the PSU is part of the problem.

Also:

Windows 7 Ultimate
6 GB ram
i7 930
creative Soundblaster XFI

latest drivers on GPU and sound card, all windows updates applied

[gamerzxz]

I can't say for sure but intuitively I would say that older games may have used a way to address the video cards memory in a way that was sloppy. They might not have released the memory properly after it use so that there was less and less available for the game leading eventually to a slow down.
Many programs do that, creating computer problems only solved by rebooting.
In newer games they must have solved that problem.
I could be wrong in the details but it seems it has something to do with bad allocation of res sources somehow.