Is my GPU dying? or something else

[Mohonri]

I'm running a Radeon HD 3850 (old, yes, I know), and on Sunday I started seeing some odd behavior. When coming out of standby, the displays did not initialize. The rest of the computer seemed to be functional--occasional flashes from the HDD light, etc. When doing a cold boot, the same symptoms were present--normal hard drive activity for a boot, but no display.

I rebuilt the computer, transplanting it to a new case. It booted and ran just fine from the onboard graphics when I booted it without the video card installed. And then it booted fine with the card installed. No issues between then and last night. Last night I put the computer in standby before going to bed, and this morning I get the same behavior as on Sunday: no display, but normal activity otherwise (as far as I can tell). There's nothing on a cold boot, which means it can't be a driver issue, so the most logical culprit is the video card.

Am I going nuts, or does it make sense? And if I have to replace my GPU, what would be a suitable replacement?

 

[sirmonkey1985]

or the motherboard isn't switching from the onboard to dedicated card when you come out of sleep unless you manually disabled the onboard video. but i'd check everything else first. i've had this issue with memory going bad as well. thought my 8800GT finally died on me, decided as a last resort to check the memory and low and behold it was the ram though i was able to fix it by swapping the slots the ram was in. so i got lucky.

also check in your bios and see if maybe the cmos battery died and it reset the sleep mode to S1 or S2 instead of S3 mode.

 

[The Mac]

also make sure you bios is up to date, there are many reports of monitors not coming up after sleep, and they are mostly bios/PciE related...

 

[Mohonri]

Thanks for the tips--I'll check for BIOS updates tonight and test the RAM. When I transplanted the hardware, the intake filters on the case were all clogged with dust, but I'm not convinced that it's a heat-related failure.