Video card problems when entering fullscreen screen goes black freeze

[sergiunb]

Hello,
I am having similar problems with my system.
1. CPU Intel E2140
2. Motherboard ASUS P5KC
3. 3 GB of RAM, Kensington, DDR2, 667
4. Graphics, ASUS Radeon 3850x2 (also used an alternative card ASUS Nvidia 7300GT)

The screen goes black when :
1. playing fullscreen games after a few minutes from start (sounds and everything keep working),
2. at startup, sometimes only for a few seconds and then it restores to normal sometimes it just remains black (with sounds and everything going ).
3. The screen went black also when I installed the updated videocard drivers as it tested the refreshed rates, but it recovered after 10-20 s.
4. I stress tested the system with the Radeon card using BurnInTest SW, with 100% load on CPU, RAM and 2D,3D graphics and the tests passed. However , when testing fullscreen, on the transition from full to normal , the screen went black for about 10s.

The system also randomly freezes while performing easier tasks such as playing music or browsing the Web, I cannot reproduce this problem since I can't figure out what is causing it.
I switched to a "weaker" video card, the NVidia 7300 GT and the same problem occured.
Drivers are the latest.
I replaced the PSU unit with a newer better protected one, 500W High Power with over 80% efficiency (I still suspect that it may somehow be underpowered) the problems are still present.
I am currently suspecting the motherboard to be at fault but don't know how to be certain.
This is really bugging me , if you could be of assistance I would be very grateful.


P.S.
The Radeon graphics adapter is a big power drain . It normally uses a 6 pin and an 8 pin connector (12V) . I went around the problem by using 2 6 pin connectors and shorting the last 2 pins of the 8 pin socket on the card. This got the card to work without using the 12V supply I just can't overclock or use SLI . Anyway , do you think this might in some way have damaged the motherboard?

 

[sergiunb]

update:
1. Reflashed the BIOS and it still doesn't work. If anything, it made the problem worst.
I now have to restart in Safe Mode to get the damned video card and monitor to communicate properly.
If I delete the drivers the system will boot in normal mode but only until it updates the drivers and the it's back to black screen at boot up.

 

[sergiunb]

Update, hopefully final:
I suspect my problems have actually been caused by 3 actors:
1. Cooling problem causing the system freeze - I've opened the case and left it opened and installed a second fan directly on the VGA
2. Monitor , the damned thing had to be reset, never would have thought of that if one test wouldn't have thrown it into a impossible resolution which forced me to disconnect it from the power net.
3. Drivers - when entering some games the monitor goes dark, still now I can Alt + TAB it back to windows where it works fine. I did not do anything but avoid those games but still, knowing it's there , the problem is half solved, right ?

These were my fixes and the PC has been running fine for the last week. Hope it helps anyone with my problem.