Maximum PC

i have 2x GFX cards running in Crossfire, Sapphire 5870s. Plugged into the top card is a 17" VGA Samsung and a 25" HDMI samsung. For some reason today the 17" has started jittering and flikering and distorting when i move windows, change pages, and just randomly whenever it feels like it. Its really bad. I cant tell if its the GFX cards or what? Anyone have any ideas?

Power down the computer, remove the crossfire bridge, and hook each monitor up to each card independently, see if the problem is still there or goes away. If it goes away, attach both monitors to one card, and recheck, then check on the other card, If you duplicate the problem all 3 ways, I would say it could be a cable or the monitor. If it only happens when the crossfire bridge is attached, then try a new bridge, if that doesn't help, I would say you have a card acting.

Ok will try all that tonight, though right now the flickering has stopped on my smaller screen and is now on my larger screen, i feel like that confirms its my card....ugh. Pricy replacement, and the 7990s arent out yet

Overclocking the 5000 series Radeon's can cause screen flicker. So can running two displays requiring different refresh rates. This is not specific to CrossfireX configs either. Single Radeon 5830's were widely reported to suffer from this issue when running multiple screens.