I hate to dig this dead thread up again. I just want to make sure that nobody makes the same mistake I did.
As it turns out the new Radeon 5 series (I assume 6 series as well) cards are known to have problems with nForce4 northbridges. When I put the 5 series card in my nForce4 motherboard, it does not POST. I emailed abit for support only to find out that they do not exist as of 2008 so I am out of luck. Anybody want a Radeon 5830?
If you are planning on putting a new Radeon card in your nForce4 machine lying around, make sure that your motherboard manufacturer has put out a BIOS update for compatibility before buying your new Radeon card. I hope that helps someone!
I have an A8N-SLI from 2006 that has never seen a BIOS update which works just fine with a 5770.