Ok, I bought 2 brand-new Powercolor Radeon HD 7870XT cards and installed them. I've had 2 Radeon HD 4870s in crossfire for 4 years and have never encountered this kind of problem before. I'll start with my system components and stats and then explain the problem:
CPU: AMD FX-8350
Motherboard: Gigabyte GA-990FXA-UD3 BIOS revision F9 (latest non-beta)
RAM: 16GB UMAX Cetus DDR3-1333 (4x4GB)
PSU: OCZ Z-Series 1000W Modular 80+ Gold-Certified
OS: Windows 7 x64 SP1, fully updated
Ok, now that I have that out of the way, when I use one card alone, everything is fine. When I have 2 cards installed but crossfire is not enabled, everything seems fine. As soon as I enable crossfire, the following things happen:
1.) Windows Performance Index test causes a system freeze at Direct3D 10 Batch Assessment
2.) Restart and Shutdown both shut down windows but the computer will not turn off or restart. It just sits there with a black screen.
3.) Any attempt to even load 3DMark causes the system to freeze.
4.) Any attempt to disable crossfire or uninstall the drivers results in a monitor-off system crash.
5.) Upon logging in, the screen remains black longer than usual and there are a few coloured lines across the screen. The login music plays to a black screen and then the login prompt pops up.
Now, I've returned the original two cards and am now on my second set. I do not know what is causing this and it's driving me nuts. My two Radeon HD 4870s which I've had in crossfire for the longest time both work flawlessly. I've tried 4 different driver sets and nothing seems to make any difference. Does anyone have any idea what is going on with my system? I've been building computers for 25 years and I am completely stumped as to what is causing all this. I got a great deal on the cards and I'm really starting to lose my mind over this.
Intel is SATAN and nVidia sits at Intel's left hand.