Asrock extreme 6 z170 Main pci lane running at x4

shurley1 wrote: i got a secont gtx 970 yesterday i opened up gpuz and it says my main x16 slot (closest to the cpu) is running at x4 mode 3.0. So i switched to the other card in gpuz and it says it is running at x8, the speed it should be at. I didn't think i could even sli on a x4 electronic connection.  So i started running the 3d stress test and it didn't move from 4x.  I started moving card around, Running with each card in the main slot and both of them wont go past x4 speed. Both of them will run at x8 in the second slot. I didn't even try the last slot since it a native 4 anyways so no information to be gained there. I have been googling all day trying to find an answer and came up with nothing. so i decided i would try here. I tried: Re seating the cpu Cleaning the contacts for the cards and the pci slot with an air compressor Flashing back bios Reinstalling the drivers with ddu Just incase im running an I3 6100 with 8gb Avexir ddr 2666 and a 750w evga psu. The last i remember the slot used to run in x16 but that was a few weeks ago last i checked. I use this rig for folding sometimes and was playing with different settings so i watch gpuz alot. Could that lane be shot? should i RMA?

Nvidia dual SLI won't work with an x4 connection as far as I know too, particularly for the main card being used. Your monitor(s) are connected to the card in the PCIE2 slot, right?

The three PCIe x16 physical sized slots are labeled, from top to bottom, PCIE2, PCIE4, and PCIE6.

You don't have anything in the PCIE6 slot at all, right? If you did, that slot shares the 16 PCIe 3.0 lanes from the CPU, so IF the PCIE6 slot was being used, the 16 PCIe 3.0 lanes would be x8 x4 x4 electrically for the PCIE2, PCIE4, and PCIE6 slots.

I would suggest clearing the UEFI/BIOS, but you said you flashed the UEFI/BIOS again, with the same version? Flashing it also causes a UEFI clear to happen. Did you have both cards in the board when you flashed the UEFI?

I think GPU-Z is wrong. Did you try another program to check the PCIe lane allocation? Can you see anything in the NVIDIA Control panel about the PCIe lane allocation for the video cards?

You are thinking about sending the board in for an RMA because ONE program is telling you one of the cards is running in x4 mode, but is that enough information or evidence to make that decision? As you said, you should not be able to be in SLI mode if one card is running at x4. You should research this situation more before considering an RMA of the mother board. I would not depend only on GPU-Z to decide there is a problem.