I already ugraded the PSU to 650w. (The brand is ultra, which I read can be faulty sometimes).
The first card I tried was the Nvidia 9800 GTX- I BARELY got the card to fit, had to really maneuver it and take out the harddrive but I got it in there. When I started up the system, the fan and lights on the card were working but there was "no signal" to the monitor. I looked around online and realized that other people had problems getting this card to work, so I just figured it might not be compatible with the Dell motherboard. Re-installed old video card. This still works.
Second card- I just got a HIS Radeon 6850. I thought this would work since I did a search and saw some references that people managed to get this card working in their 531. And the card is backwards compatible, so it should work. But the same issue- "no signal" to monitor. (It is seated correctly, and the 6 pin connector is plugged in securely.)
I have tried: updating the BIOS, taking out the battery, used driver sweep to make sure I got rid of old Nvidia drivers, reseated the memory.
What else can I try???!
If I have a faulty PSU, how can I tell? I don't have the extra money to buy another one just to check to see if that could be the case... I know the 531 isn't a good setup for using these graphics cards but I'm trying to save for a new system- I thought getting a good graphics card would at least improve performance for a few months until I can get another system that can use the card to its full potential. Is there something I am missing that definitely has to be upgraded for these cards to work???
Any advice would be very appreciated! BECAUSE I AM GOING INSANE TRYING TO FIGURE THIS OUT.