Suddenly black screen and fans at full speed while gaming, then no display on boot

[battlegoat1]

I had many black screen errors when playing games in the past 6 months, but they were solved by turning off PSU then rebooting the system. The same happened now, but this time my fans started spinning really loud at full speed, then i get black screen on boot (the comupter turns on, all fans are spinning normally).

I'm guessing the problem is either with the PSU or the GPU, I've read countless threads on the issue, but couldnt find a solution, so i'm posting the symptoms here in the hope of someone can estimate which one is the faulty part.

The specs are:
CPU: i5 2500k (factory clock)
GPU: MSI HD7950 Twin Frozr 3 (factory clock)
Mobo: Asrock z68 gen3 extrme3
PSU: Cooler Master GX 550W
RAM: 12GB Kingston HyperX 1600Mhz
Display: Dell U2412M

My PC is 7 years old, so RMA isn't an option, and i don't have access to another PSU or GPU to do some testing. I monitored my system after countless black screen freezes, but got nothing useful out of it, all tempretures are normal, drivers are up-to-date, changed PSU cables, power outlet slots, monitor cables, tried hdmi slot instead of dvi, replaced thermal paste, etc, no improvement.

But now that i'm getting no display i did some testing, i hope these clues will be enough to point towards what's causing the issue:

- turned on and off my pc 5 times to see if it repairs itself -> no display
- plugged the monitor into the motherboard -> no display
- removed the gpu -> now the monitor works and i can use my pc
- then i put the gpu back with the monitor still plugged into the mobo -> no display
- unattached both 6pin connectors from the gpu -> getting display from the mobo again
- reattached one of the 6pin connectors -> still getting display
- reattached the 2nd 6pin connectors -> no display

And now the best part:
- plugged the monitor back into the gpu -> display works, i can play games again... until the next black screen, which probably will be the same as now where a simple restart won't solve the problem, and these constant freezes might even harm the system

So what should i replace, my PSU or GPU?

Apologies for the long post, and thanks for any input you can give!

 

[norcalsc]

Honestly sounds like the gpu is failing and also like the psu is failing. They're both SEVEN YEARS OLD.somethings got to give, 50 50 chance it's one or the other. Hard to say as it is intermittent

 

[battlegoat1]

Thanks for your reply, i forgot to say the GPU is "only" 4 years old, tho i guess that's still quite old. Probably i'll try to replace the PSU first as it's cheaper, then the GPU if the problem remains.