[SOLVED] Can’t use both short PCIe 2.0 slots at the same time on Sabertooth X79 Mobo?

Feb 1, 2019
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Hey guys,

I have a Asus Sabertooth X79 mobo and currently it has installed, an Asus GTX 1070 Dual gpu in the bottom most tan coloured pcie 16x slot, above that it has a sound card installed in one of the shorter pcie 2.0 slots with another short pcie 2.0 slot available above the soundcard and no other lanes used. When I plug another expansion card in - in this case an inatek USB 3.0 card into the other available short pcie 2.0 slot and boot up my machine, I lose access to 2 of the 4 installed SSD drives and one of my larger backup mechanical Seagate barracudas. All internally installed drives. Why is this happening? Is it a configuration in the bios I’m not switching? The USB expansion card installs and works and windows sees it but I lose those aforementioned hard drives? If I uninstall the USB explanation card things go back to normal. Is there a limit on the cards I can install into this mobo?

Thanks for any help guys.

Cheers.
 

Zedjulz316

Reputable
Oct 9, 2015
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4,860
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This looks like a chipset issue. The X79 platform has 40 lanes built into the CPU, plenty for what you're trying to do. Try to move the GPU to the top slot and run the smaller cards on the bottom slot. You can also try to run your GPU in 8x, maybe that will allow for the card to run properly. Don't worry too much about your GPU, 16x and 8x have a 2-3% difference in effective performance.

To be honest, I don't have much experience with issues like this but I hope one of my methods will help.
 

Zedjulz316

Reputable
Oct 9, 2015
182
0
4,860
65
This looks like a chipset issue. The X79 platform has 40 lanes built into the CPU, plenty for what you're trying to do. Try to move the GPU to the top slot and run the smaller cards on the bottom slot. You can also try to run your GPU in 8x, maybe that will allow for the card to run properly. Don't worry too much about your GPU, 16x and 8x have a 2-3% difference in effective performance.

To be honest, I don't have much experience with issues like this but I hope one of my methods will help.
 

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