Sapphire HD 7950 not working or something else?

[mufasa]

Hello,

I recently purchased a HD 7950,very happy with how it works, except for once every now and then the computer hangs for a second, all the fans spin up loud and it restarts. It seems to happen randomly: browsing the web, playing games under heavy load, playing games under light load. At first I thought it was an OC problem but I have reverted everything to stock and it has occurred once more.I did take the power supply cover off and cleaned it thoroughly before the card was installed. Now I am going to plug my old 6870 in for a while and see if it is indeed the card and not perhaps the PSU getting old or some other component. The set up is very stable otherwise, even running furmark/prime 95 to load everything to 100% for 15 mins
Any and all advice is appreciated as I would really not want to have to deal with returning the card and getting another.

Gigabyte 880gm-usb3 mobo
phenom ii x6 1055t
12 gb ddr3 ram
corsair tx750 psu
2X 1tb hdd
3X 80mm fans
was running a HD 7950 but switching it out for HD 6870 to test

 

[Remixex]

A part that can cause hang on all the PC...sounds weird, i would think that if the GPU is faulty your display might just disappear and yo uGPU stop working and then restart, but why whole computer? how is your PC running with the 6870? i would like to know how are the Temps on your PC, you can use AMD overdrive program to look at them with little error margin
http://sites.amd.com/us/game/downloads/amd-overdrive/Pages/overview.aspx
i would blame the PSU or the MOBO for a full restart, but if your system works correctly with the 6870 then that only reduces to PSU or GPU (considering the 7950 uses more watts)
I'm not an expert on the topic, but i'll try to help

 

[mufasa]

The temps I get from overdrive are odd as they don't agree with cpu-z or furmark or core temp. I also noticed that for some reason I have a core that will jump from 1.425 to 1.475 volts which I have included in the pics below,the affected core is random and it can be seen in both overdrive and core temp. The temps from temp core always seem to be good, cpu stays below 50C and GPU never above 70C except for furmark

1.425 V
1.475
temps

 

[Remixex]

They agree, what overdrive is giving you is a MARGIN not the ACTUAL temp, the margin is how far below are you from reaching limit Tº, if under load your margin temp turns red something is wrong, voltages are strange, this is from CPU world=


V core 1.075V - 1.375V (at rated frequency)
1.225V - 1.425V (Turbo Core mode)
0.975V - 1.175V (Minimum performance state)

I take it you overclocked in the past, maybe that messed up some cores voltages, it shouldn't go up 1425...
How did your pc work with the 6870?

 

[mufasa]

When I booted up BIOS it had the default Voltage set to 1.475, after loading optimized defaults it displayed 1.425. Still rather high so I think I will manually lower it. I have not had a chance to test the computer all day, but will try to see if it fails with the 6870 sometime soon. And thanks on the heads up for amd overdrive, because that confused me for a while.I did overclock it a few days ago, but have went back to default settings for a day or so.