A friend installed 4850 into the PCI-E slot 4, giving me a total of four 4850's. I booted normal, went into ATI Catalist controll center, under the Xfire tab and noted it was set to enable 3 graghics cards, I than opened the drop down box and chose 4 GPU's and than clicked the apply radio button. The screen blanked out for a second and returned to the BSOD. I remove the problem card and rebooted normally. K now I am out of idea's Guy's. Bad card? what you think?