Black screen with new vid card

[danasa]

Powered my computer the other day and got no signal from my Sapphire x1900xtx. I got a Sapphire hd 4850 to replace it. I can boot in safe with the 1900 installed. I get nothing with the 4850. Windows is booting, just no signal to monitor. Wut up? Thanks.... (checked voltages in bios.....seems fine)

XFX nForce 680i LT SLI NVIDIA Socket 775 ATX Motherboard
Intel Core 2 Quad Q6600 2.40GHz
Ultra 500-Watt Power Supply
XP Pro/sp3

 

[danasa]

Got signal to monitor with vga cable instead of dvi. Installed update drivers. Why no dvi signal? When I open Premiere Pro it asks to reactivate and then locks when I click 'yes'. Any thoughts? Driver problem or is this card a lemon?