Problems booting with Crossfire HD 6950's

I've looked all over and can't find a fix to this issue. I recently purchased two ATI Radeon HD 6950 cards, both in perfect working condition, and alone run fine in my PC, however once I try to crossfire them my PC won't boot. Nothing comes up on the screen, none of the peripherals flash, however the PC sounds as if it is running, the Cards cycle between the fan at max and resting speeds, and the Q-code cycles through all of the boot/ini codes.

I've tried running it with both cards not connected, but it doesn't work either. The PSU (900w Antec) is supposedly Crossfire ready (http://www.newegg.com/Product/Product.aspx?Item=N82E16817371050), and the board (Crosshair V Formula-Z) is Crossfire ready. I've gone through the bios and can't find any option that would be blocking this and the correct drivers are installed. Any help?
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More about problems booting crossfire 6950
  1. You're saying one single card does not work? Are starting from scratch or already have windows installed? How far it get on screen and what beep do you hear?
  2. Both cards work perfectly fine, just not together. Windows 7 64bit is already installed. No beeps, It doesn't get far enough to see any image on the screen
  3. i met with some what similar problem, i my case the monitor said 'nothing connected' (words to that effect). i tried many things, thought may be static was behind this, took out the battery reinserted it, no dice. removed one crossfire bridge, removed both (the computer sounded an alarm), nothing. took out each card they were working individually. inserted both cards, this time connected the hdmi cable to the other card, reconnected it. tried dvi, then went back to hdmi and it worked.
    if u can find sense in it, good luck
  4. So you're saying you can boot to windows with both installed as long as the Crossfire bridge isn't connected, or you can boot to windows as long as your don't install the second card ?
  5. Windows will only boot if one card is installed. If both are installed, windows will not boot (whether or not they are bridged). I've also tried moving them around to make sure is wasn't an issue with the PCI-E socket, but they seem all good.

    Reply to dicfeynman: I am not using a case monitor. I am only using a single screen via DVI to the first card (closest to cpu). I have no plans on using the HDMI
  6. let me get this straight, you can see the POST screen when both are inserted and connected via cf bridge.
    and the problem is that u cant boot into windows ?
    if thats the case then it a software problem. try safe mode- uninstall old display driver or live linux knoppix or something see if they r recognizing both cards. or
    google sfc scannow, scanboot, boot with windows installation disk do a repair.
  7. Please look over the post carefully dicfeynman, With BOTH installed (with or without bridge) I cannot get to the post screen. The screen does not display anything. No peripherals light nothing. The computer does however spin up the fans for gpu, cpu, psu, etc.
  8. Weird issue.

    Stupid question, have you updated all your drivers to the latest versions including your BIOS?

    I had a few crossfire issues with my setup when I added my 2nd 6950 4 months later. But after updating the BIOS no issues.

    PS, I'm using both crossfire bridges
  9. What size Power Supply do you have installed? To much draw from the 2nd card could drain juice from other important parts that are needed to boot.
    Check it Out
    herculesx
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