I would suspect your adapter.

Got a very similar problem on my Asus V9560XT/TD/128M (GeForce FX 5600 XT): DVI output is fine, but the VGA output has a strong cyan tint. Doesn't really matter as long as DVI is working fine though.

DVI-VGA adapters tend to be passive, if the red pin on one port is faulty(bad contact) and the blue pin on the other, you will get the kind of behaviour you describe.

Either bad contact or one of the capacitors or protection diode is shorted to ground. You can check resistance on the red channel to ground, it should be around 75 Ohm.

I suspect there is an inductor missing close to the DVI port that carries one of the analogue colour signals.

I have the same problem on 6800GT. Screen is all green on VGA out (BIOS, Windows). DVI is fine. I'll check the resistance...

Examine your card very carefully near the DVI connector, one of component got knocked off.

Common on my video cards that was advertised as needs repair from ebay, since I knew how to repair, that saved some money and fun.

Cheers,

pentiumspeed wrote on 2021-11-25, 01:07:

Examine your card very carefully near the DVI connector, one of component got knocked off.

Common on my video cards that was advertised as needs repair from ebay, since I knew how to repair, that saved some money and fun.

Cheers,

Just took a hard look on the back side near the VGA connector and it seems at least two smd's got knocked off. Now I know where the problem lies. Thanks for the hint 😉

Lucky you.
I have S3 Trio64v2 that has blue output shorted to the ground. I was hoping that's some external components, but after removing everything (inductor, 75 Ohm resistor, etc) the pin on the chip itself measures 12 Ohm to the ground.