So I have 2 5870s connected via HDMI to an Asus VK246H (I'm using HDMI Audio for sound). In games, I get a flickering, like when a camera tries to record an old TV. The monitor is set to 1920x1080@60hz in Windows and in CCC, but even in games that have a refresh rate setting, I get flickering. Strangely, things like Furmark at full screen don't flicker, and neither does Windows.
On that note, for some reason my GPUs are at 99% usage the entire time, even when I'm just in Windows. Could it be the HDMI Audio?
Is the flickering constant in the games, or does it just happen at particular times?
I had a 5850 crossfire setup that would flicker in Medal of Honor when I was close to a wall. Also, it would flicker a lot when playing BFBC2 in general. Hawx and Left4Dead on the other hand, would work fine with no flicker. I would experience occassional flicker when playing NBA2k11 but that cleared up completely with the 10.12 driver release. Flickering got worse in MOH and BFBC2 in the 11.x driver releases, as well as an issue with no longer being able to install HDMI/DP Audio drivers for the cards. With 11.2 my 2nd card would stay pegged at 100% GPU usage after playing anything.
This really makes me think drivers are the culprit unless you experience the flicker constantly? You could try uninstalling and re-installing the drivers. I had to do this each time I added a card to my system (2nd then 3rd). Did you just add a second 5870 or have you run with two from the beginning?
If the flicker is constant during games, make sure the crossfire interconnect is attached correctly and re-install the drivers.
Your GPUs should hardly have any sort of load showing while just in Windows and your cards should show as downclocked in GPUz when you're in the 2D mode in Windows. Are you running with the 11.2 drivers or is the March release available?
This worked fine on my old monitor (HP w2207), I haven't touched the Crossfire connectors since I installed my second card in November. The new monitor came in February. Flicker starts as soon as I open the game, but it fixes itself sometimes (Cities XL 2011 fixed itself when I turned on AA, for one). The GPU usage problem fixed itself after a while (CCC reports both cards are between 0 and 1% on Windows, and properly downclocked) but the flicker's still around. I'm running 11.2 on 7 x64.
There have been many posts about AMD drivers issues resulting in flckering and a 99% GPU usage bug. I suggest you try an older Catalyst driver version. If 11.1 doesn't solve the issue, then 10.10's seemed to be pretty good.
The drivers are the reason I switched to Nvidia for my performance PC with multiple cards. AMD cards are great in a single-card config. I have 3 PCs in my house with single AMD cards and they all work fine at their respective levels of performance.
I had 2 then 3 5850s in crossfire. Framerates were crazy and with lowered AA comparable to what I have today (minimums were lower though), but the driver issues... I would update my drivers the day of the release hoping the most recent release would do the trick, but they never seemed to get it right for crossfire setups. The flickering was occasional, but increased in frequency in my favorite games over time (BFBC2 and MOH). On the other hand, it completely went away over time in NBA2K11.
10.12 seemed to be best (with the least flickering issues) for these games on my setup.