Whats wrong the TFT or the GPU?

Hi

I have an
nvidia 9800GT md1G,
Pentium Core2 Quad Q8400
4GB DDR3 1333MHZ (Dual Channel)
PSU Coolermaster 750Watts
Mobo DP45SG
LG W2243T dispaly (was using DVI)

Everything was working fine till one day - no display on boot. Got the LG Cust Care, engineer came changed the card containing the DVI & VGA ports. The display was back but only on VGA. He claimed the DVI on GPU was faulty. Used a DVI to VGA adapter on the GPU's DVI port and display was there. But when connecting DVi to DVI no display and the TFT won't even detect it and would simply go in "Power Saving Mode". After two months the engineer updated the firmware on the same card and the TFT detected the DVI but still no display. After another month he got the TFT replaced with the same result.

DVI on the GPU is working with DVI to VGA adapter but not directly. Does that mean that the DVI port is fine. Now if the card that he replaced earlier didn't have any firmware on it at all could it be that the replaced TFT does not have it as well. Or is it the GPU.

I cannot cross check the GPU or the TFT as nobody around has the GPU installed or the Mobo with the same slot. I even tried using a DVI-D and a DVI-A cable but to no success.