Ati saphire 4870 3 red lights

[pitastrudl]

So i've been reading about my problem, but not all seem to fit my problem.

Problem:
Under any modereate stress, pc reboots. If i try benchmarking my GPU it instantly reboots. If i try to run a video game it reboots(the pc ofc). On EACH boot, there are 3 lights that light up for a second. I can use my PC but i can't do anything extreme. I underclocked my GPU by -100mhz otherwise it would be crashing every 30 minutes. I've tried cleaning the card, cleaning everything but nothing. How can i know if the PSU is at fault or the graphics card? I've had my pc for 5 years.


CPU AMD PHENOM X4 2 840
6GB RAM DDR2
ATI RADEON 4870 SAPHIRE
MOBO GA-MA790X-DS4

 

[LazerTechX]

Does your power supply have enough wattage?

 

[RanriZedd]

it might be some dust laying around in your case. dust can fuck up ur pc so clear it out. if it doesn't work then i believe that your psu is dying.

 

[pitastrudl]

I cleared it out and it's still the same. Can i be sure that my GPU is okay but my PSU isnt?

 

[RanriZedd]

If you have another GPU try it out. If it works then its probably the GPU. if it doesnt then its probably the PSU.

 

[pitastrudl]

yeah im gonna go with that.

 

[pitastrudl]

I have replaced my PSU with a new Corsair one, now it works perfect, thanks for the help