BSoD when screen saver trying to start

Odd. That definitely sounds like some type of hardware problem. Have you tried cleaning the adapter contacts?

• "Use an ink eraser or an electrical contact treatment, available at electronics supply stores, to ensure adapter card contacts are clean" (Bug Check 0x7A: KERNEL_DATA_INPAGE_ERROR).
  
  As you add and remove hardware, follow these steps for ESD safety:
  
  1. Shut down and turn off your computer.
  2. Unplug all power supplies to the computer (AC Power then battery for laptops, AC power for desktops)
  3. Hold down the power button for 30 seconds to close the circuit and ensure all power drains from components.
  4. Make sure you are grounded by using proper grounding techniques, i.e. work on an anti-static workbench, anti-static desk, or an anti-static pad. Hold something metallic while touching it to the anti-static surface, or use an anti-static wristband to attach to the anti-static material while working. If you do not have an anti-static workbench, desk, or pad, you can use your computer tower/case by finding a metal hold in it, such as a drive bay.
  
  Once these steps have been followed, it is safe to remove and replace components within your computer.

The electrical contacts looks fine. As I have put both cards in both slots and remove them many times. I sent the defective card out to VisionTek already as I can repeat the problem. The key turning point in all this is the fact that I was able to load version 12.4 without the machine crashing and/or an incomplete install of version 12.4.

......... and after figuring out the memory issues.

Alright, let us know what VisionTek determines. Nice troubleshooting work, by the way. :)

I had issues with my 4850 with 12.3 and up, so they may have something there with the driver versions. Have you tried an older driver, or the driver they suggest?

I tried version 10.4 and Crossfire works. However, my game needs version 11.7 so I have version 11.7 now. Still works. That is, I can crossfire and when running Battlefield 3 the second GPU is slightly active (only got up to 19% load when the first GPU reached 100%). If I go even high resolution, the 2nd GPU will not have an increased load.


Sent from my iPhone

Try uninstalling all graphics drivers and letting Windows install the appropriate drivers. It may have the best, up to date drivers for the 4850. I know it installs a good driver for my system with my 4850. :)

Oh, I did that before - also works. I guess I cannot crossfire unless I have the correct version of CCC


Sent from my iPhone

Here is the most likely candidate for the software that goes with the driver Windows Update installs: Previous ATI Catalyst Version 11.6

I have download 11.6 and tried it before. Again, my game needs 11.7 and 11.7 does work. I am still monitoring the second GPU's load. May go to 11.8 or even higher. I have downloaded all versions from 11.6 through 12.4 plus 10.4 through 10.12.