Graphics Cards

[sketterman]

Hey Everyone,

Fairly versed PC builder here, but my last build was 7-ish years ago.  Not sure if I'm just rusty or if I've got a bad GPU on my hands.

The short of it - overhauled my entire rig.  Picked up ASROCK Phantom Gaming Z690 MOBO, new RAM, 13600kf CPU, and a 6950XT.  GPU deal was awesome; $599 plus The Last of Us.  I couldn't resist.  It was time to upgrade anyway.

Got everything built, machine wouldn't POST.  I had lights, fans, LED's, but no USB and no video output.  Remembering that my CPU needs a BIOS flash in order to work, I did that, and at that point I now had USB functionality, but still no display.

After reseating everything, trying the 1-RAM stick trick, multiple cables, and trying each output on the GPU, I then looked at the MOBO.  PSC has a red light that stays illuminated for "VGA".  So I pulled the 6950 and installed my old GPU (GTX 1080).  PSC light goes off, machine boots into BIOS.  I had unplugged all of my drives for t/s purposes.  Now that I know the MOBO is good, I reinstalled the 6950.  Same issue.  PSC light for VGA is illuminated, no display on the monitor.

Is this conclusive the GPU is faulty?  It does 'power up'.  The LED's are lit, but none of the fans spin.  I wasn't sure if that was normal since the GPU isn't under any load.

Also - does this card REQUIRE all three 8-pin connections?  I only have two at the moment.  Going to pick up a 3rd to test, but I assume the GPU should still function, maybe just nerfed in performance a bit. 

In any case, looking for any guidance on if I should just get a replacement for this, or if there is other options I can try first.  Any and all feedback is greatly appreciated!

Shaun

[Aria__ · Accepted solution]

"Also - does this card REQUIRE all three 8-pin connections?  I only have two at the moment.  Going to pick up a 3rd to test, but I assume the GPU should still function, maybe just nerfed in performance a bit. "
This part is most likely the culprit. It can still be a DOA but I'd highly recommend getting the required cable, also make sure it's compatible with your PSU.

[sketterman]

Hey Aria,

Thanks for the reply.  I never knew GPU's had a "QVL" for PSUs.  I don't see my exact model on the list.  I have a Cooler Master Silent Pro M 1000W.  The list for the GPU shows hybrid versions.  In any case, I'm confident I have the wattage.  

In any case, I've got a 3rd 8 pin arriving tomorrow.  I'll test it and see how it goes.  Newegg is already processing the return in the event it still doesn't work. 

[Aria__]

I  hope it'll work out for ya!

[sketterman]

This was it.  I've had everything up and running for a few days now, just forgot to come back here and update.  With all three 8-pin connectors, I'm now good to go.  Many thanks for the heads up, glad I didn't need to do any returns / more waiting!

Shaun

[Aria__]

I'm glad it worked out! have fun with your new gpu!

[schldskjoirz]

The 6950 XT should work without problems with two cables. The only apparent issue should be a drop in performance. My 6900 XT otherwise works normally even with one cable, but in this case the PC hangs up or crashes under heavy load, such as editing high resolution images and playing games. To me, it doesn't sound quite normal that your PC won't even boot properly if the graphics card isn't powered up with all the three cables. If there are any faults with it, I hope they come out soon, and not right after the warranty period.

[sketterman]

Interesting.  Well for one thing, my PC *would* boot without the GPU being powered properly; the initial reason for it not POSTing was because I needed to flash the BIOS first with the new i5/z690 MOBO.  Once I did that, everything was fine minus the video output from the 6950 XT.  That's where I was for the OP; PC would boot up just fine if I had my old GPU plugged in, but with the 6950 XT I had no video output.  I may have worded it funky.

As far as the physical power connections go, the only other thing I can think of is the PSU that I had previously had 6-pin to 6+2-pin PCIe connectors (with JUST 6-pin at the PSU), where as the one I have now are 8-pin to 6+2-pin, with all 8 pins at the PSU.  With the old PSU, the GPU would light up, but the fans did not spin, which, to me, is indicative of a lack of power.  I'm definitely not an expert, though.

Shaun