Need help with Crossfire

New to actually doing crossfire instead of reading about it. I have a seriously strange problem.
I have two HDs installed, one with a full boat Win 7 ultimate 64 bit and traditional HD.
The second is Win 8.1 on an EVO SSD 512 meg.

The video cards are both Sapphire Dual X, one 7950, one 280X. I installed the card, booted to 8.1, the card was not recognized by CCC so I removed all drivers, removed card and driver in control panel and rebooted. The installed CCC again, this time the card was recognized and I enabled CF. Any game I tried crashed in a few seconds, black screen, even locking the PC. I pulled the CF bridge.
I decided to take a look and booted Win7, CCC immediately recognized the cards, told me I needed to connect the bridge, shut down connected bridge and booted. Played AC4, Bioshock infinite, COD ghost, all with no profiles installed. The cards worked and my temps were great.
What the _)*&*& is going on in Win 8.1 ????
Crosshair V MB. 16 gigs ram, no OC. AMD 8350, no OC. 1K Rosewill pwr. supply.
1.5 TB HD and a 512 SSD.
Any suggestions?

Sounds like something went wonky with Win 8.1 installation, or a boot-program is trying to sync the card clocks automatically.

I have one machine with 2x 280x in CF working in Win 8.1. Try to uninstall the drivers, shut-down, plug-in the CF bridge if it isn't, boot Win 8.1, install 14.4 drivers, reboot, check in CCC to confirm if you are in CF mode. Run Valley benchmark or something similar to confirm both cards are working.

Also, make sure not to run Afterburner, Trixx, or other such programs who might try to synchronize the clocks of both cards which can crash the system since the 7950 might not be able to hold the 280x clocks. Maybe you have one on the Win 8.1 machine, but not in Win 7, worth a check.

Thanks, I have to agree that those are good suggestions. Followed them all in the 8.1 installation. Trixx was installed on the Win 7 HD and everything came up perfectly. I had tested the 7950 previously and it had no problem holding the same mem and gpu settings as the 280X.

That's great you got things working. I gotta say, I have been curious about CFX'n 2 gpu's of 2 diff gen's. I tried this once with a 6950 and a 7970, wouldn't work. But I never really considered the 280x, because I know it isn't the same gpu family as the 290 or 290x, its a Tahiti just like the 7000 series cards. So I can see how that would work with a 79xx series card.

Stay [H]

Works great immediately on my Win 7 installation, but still won't run games on Win 8.1. LOL.

Unfortunately, short of an early rollback or complete Win 8.1 re-install I'm not sure what to suggest. I've done a number of rigs and something seems just off on the Win 8 install if it isn't playing nice.