I have been working on this for weeks and am about to the end of my rope.
My first two PCIe x16 slots just stopped detecting any video card in them. When I plugged in to onboard, I was able to confirm that nothing was being detected.
I could get an old nVidia Quadro card to post in PCIe 3 and work secondary to the on board, but never again got get the other to slots working. Wide card would not fit in bottom slot.
I have since RMA'd my board and recieved the new one. It isn't doing exactly the same thing, but very similar. It's not consistent on what display adapter it wants to post with and has had me guessing for hours.
I do have both of my M.2 sockets occupied and am fully aware that you have to be careful when configuring particular setups with Sata, NVMe, and PCIe that they don't interfere with each other.
With that said, I took the time to try every conceivable thing I could think of. I enabled the setting for the m.2 expansion card to try that as well as set PCIe 3 to 2x, disabling SATA 5 & 6 in the process.
I got absolutely nothing from either main PCIe slot. Surely they don't expect you to give up video performance to use NVMe storage? The way I read it, it should not effect PCIe x16 1 at all.
Here is the craziest part. I stuck an older Quadro in PCIe2 to see if it would work. It made my main GTX 1070 start working. I still had to jack with the BIOS settings to get onboard disabled completely, but my main video card is working again.
The only problem is that I still have an ugly Quadro sitting in slot two that cannot be detected by BIOS or OS. If I remove it I lose my main video. Also, my first PCIe slot is only running 8x 3.0, which is disappointing.
Sorry about the long post. I've just been beating my head against the wall to get this figured out. Firmware issue with the GTX 1070? I used Nvidia's tool to update that. Should I remove on of the M.2 boards? I don't feel like I should have to do that.
Thanks in advance for the assistance,.