My old video card just died. I originally had an EVGA e-GeForce 8800GTS with 640 megs of ram and ram went bad in it, so it's basically fried. I got it in November of 2007 for a whopping $579.99 when it first came out because it was the first video card (I do believe) that supported Direct X 10.
Did you buy from evga/xfx they offer lifetime warranty see if the manufactor can replace it. If not time for an upgrade. The 4850 is noticeable faster but i would recommend a 4870 instead since there priced similarly.
I contacted EVGA earlier today but I, unfortunately, forgot to register the video card when I first got it. Talked to support and they told me to email email@example.com to see if they could help me. I am looking at worst case scenario as I know I probably wont luck out on getting a refurbed card from EVGA.