GPU SLI/PCIe Problem (x4?!?!)

Epif

Distinguished
Jan 11, 2015
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18,510
So I originally purchased a Zotac GTX 970 and have been loving it. Decided to buy a second one, same exact model, to try SLI. When I couldn't get SLI to work I thought it might be the SLI bridge but just to be safe I pulled out my first card and put my new second card into the main slot. This brand new card is now running at PCIe 3.0 x4 for some reason, even under load. My original runs at x16 no problem in the exact same slot. I've never heard of anything like this happening before, but if I had to guess this is why running in SLI isn't possible. Do I somehow just have a bad card?
 
Solution
your board supports SLI so that should not be a problem, plus if it's the only card in the system as you stated for testing it shouldn't be a problem regardless...then my guess is your second card is damaged. whether it be some of the pins on the PCIe side causing it to drop PCIe lanes down to four or an improper firmware was installed at the factory. Regardless I would look into returning your card.

Epif

Distinguished
Jan 11, 2015
13
0
18,510
ASUS Z170A

But remember now, it runs at x4 even when it is the only card in the system and in the same main slot that runs my original card at x16.
 

atomicWAR

Glorious
Ambassador
your board supports SLI so that should not be a problem, plus if it's the only card in the system as you stated for testing it shouldn't be a problem regardless...then my guess is your second card is damaged. whether it be some of the pins on the PCIe side causing it to drop PCIe lanes down to four or an improper firmware was installed at the factory. Regardless I would look into returning your card.
 
Solution

atomicWAR

Glorious
Ambassador


He stated above he tested the card in the primary slot alone. So the slot is wired for 16x and he is only getting 4x speeds. i have heard of this happening before for the same reasons i mentioned, either damage to the graphics card's PCIe interface or a bad firmware flashed at the factory for the GPU are most likely offenders. If he misspoke and did not move the card and left it in the 4x slot it's a different story.