Need help Problems adding a 3rd gpu

NoruneNorune Member Posts: 3
Current pc:

2x Fury x
i7 6700k
Asus z 170k
1000w psu

I am trying to add an hd 7970 but my pc always freezes before going to windows. I am using a 3.0 1x to 3.0 16x riser for the 7970. Everything except the 7970 is powered by a 1000w psu and the 7970 is being powered by a 600w psu. The riser is connected to the 1000w psu as well.

I tested the riser with an old 6670 which is powered solely by the riser and it goes to windows and is detected.

On its own the 7970 works as does the 600w psu. Also before buying the 1000w psu I was running fine with dual 600w psu.

My only idea is it has something to do with pcie lanes perhaps. On the asus website for this motherboard it says it is compatible with quad crossfire setups(Although perhaps it means 2 dual gpu like a 7990). Currently I am running fury x crossfire and mining just fine with the amd driver panel displaying 1 card as x4 and the other as x16. I cannot find anywhere in the bios to modify bus speeds. Worth noting perhaps is the 6670 only supports pcie 2.1

Looking at the manual it explains only up to dual gpu usage for pcie express operating mode. Again though the manual also says it supports quadfire.

Best Answer

  • kurthunkkurthunk Member Posts: 17
    Accepted Answer
    I would run your 2nd and 3rd cards from risers from the pcie x1 slots.

    But, you could also try slowing down the pcie to free up more lanes. From the manual for your mobo you can change the generation of pcie. Try setting the speed to gen2 which is half the speed of gen3, but won't affect mining.

    2.6.4 PCH-IO Configuration
    This item allows you to con gure the PCI Express con guration settings.
    PCI Express Configuration PCIe Speed [Auto]
    Allows you to con gure the PCIe speed. Con guration options: [Auto] [Gen1] [Gen2] [Gen3]


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