help needed... odd behavior but only with crossfire

[xeddex]

Hi all; first off thank you in advance.

I just got my second xfx 5850 yesterday. It's the same model as my first 5850. Whenever I enable crossfire in ccc I get stuttering/jerky behavior in games. Even in NON 3D games. I am running 2 crossfire bridges.

ex: Plants vs Zombie. No 3D but it's stuttering/jerky. I disable crossfire and it's smooth as can be.

ex: Team fortress 2, Same thing, jerky and stuttering but I disable crossfire and it's smooth.

If I turn on net graph in team fortress 2 I get 200+ fps and even though it's jerky and stuttering (but still playable) the net graph numbers never drop.

I run Heaven Benchmark 2.0 with crossfire enabled and I get a very respectable score for my system (just shy of 1100 and I run an i7 920).

So the "numbers" look to me like they reflect no stuttering/jerkiness but yet I have the problem. Any ideas anyone? I have a good quality psu so I don't think power is the issue.

Latest ATI drivers + the new ATI profiles. Running Win7 64. Asus rampage ii. All temps are good. Just a mild overclock on the 920.

 

[Balthazor]

Different games behave differently with multi-gpu setups, I've found - this is true when I used SLI, as well. I found that some games have more consistent FPS with crossfire or SLI disabled.

With crossfire an easy way to do this is to create game profiles for commonly played games, keep crossfire enabled, but disable 'catalyst AI.' This prevents your cards from using crossfire profiles, forcing the game to run on one GPU, despite crossfire enabled.

I'm currently playing BioShock, and despite an avg FPS in the 250-300 range with my crossfire system, there are certain weird spots where FPS will suddenly drop to 20 or so; disabling crossfire keeps the game running smoothly at around 80 FPS.

I recently read that some people have success in removing multi-GPU stuttering by disabling hyperthreading; this didn't help me, but it is something else you could try. Otherwise, I'd just say its normal to see some stuttering in multi-gpu setups in some games.

When I was using SLI, I recall Homeworld 2 giving me a similar problem; disabled, smooth as silk.