Recently I've been having a problem with my Radeon 5770. When running any intensive games the screen will flicker and go black after what seems like a random amount of time. I cant do anything once this has happened and am forced to restart the PC. I've tried reinstalling the drivers but to no avail. Is this just a dodgy card or is there a more complicated issue? My specs are as follows:
Motherboard: Asus P8P67 LE
CPU: Intel i3-2100
GPU: SATI Radeon Sapphire VAPOR-X HD 5770
System Memory: 8gb DDR3 1600 MHz
Windows 7 Home Premium 64 Bit
Get a utility like gpuz and check the sensor tab and find what temperature the card is running at. Gpuz can even log to a txt file so you can run a game and then refer to the log file so you don't have to alt tab. For games the card really shouldn’t get over 90c under load. So anything up to 90c is fine.
The other 2 possibilities are like the other poster mentioned either power supply or video card. Unfortunately with a random issue like that it usually gets down to where you need to swap hardware components out one by one and see if the issue changes.