I am building a computer to run molecular dynamics, and I have 2 Nvidia Tesla K80s that I would like to use as accelerators. I also have an old single slot Nvidia GPU that I am using as a display out to configure the system. When I first installed the cards and powered it on, it went into the BIOS and it was able to detect 2 out of 3 graphics cards. However, now whenever I try to restart it, it fails to boot into the bios and it shows me a message saying that it is "updating LED firmware".
If I take the Tesla Cards out, it continues to the BIOS normally. I have tried multiple slots, one graphics card at a time, above 4G decoding on/off, and nothing seems to work. The documentation says that the cards use PCIe Gen 3 x16, and the processor (Threadripper 2960x) supports 64 lanes which should be more than enough.
What should I do to get it working, considering that it was able to detect one of the Teslas?
EDIT: Motherboard: ASUS ROG STRIX X399-E CPU: Threadripper 2960x GPUs (Issue): Nvidia Tesla K80 x2
UPDATE: I am now able to see one of the Tesla GPUs in the BIOS. I just have to keep rebooting, and eventually, by chance, it boots into the bios. Once inside, however, it only detects one card. I tried removing the card that works and booting it up and that also works, so it is unclear why both of them don't get recognized in the bios nor in the OS (Ubuntu 18.04)