TLDR is at the bottom of the post.


I have two 2-slot GPU's in my system, so unfortunately PCIe8_2 and PCIe8_4 slots are mostly covered. I wanted to use one of those extra slots to mount another M.2 SSD on an expansion card so I thought I'd try using a thin-looking and high-performance riser extension cable which would give me enough room. The plan was to serve a PCIe expansion card on which I could mount a second PCIe NVME M.2 drive on it. I have a 256G Samsung 950 Pro M.2 lying around, and I bought a X4 PCIe 3.0 NVMe - M.2 SSD adapter on Newegg.

THE DRIVE

THE CARD

It simply turns out that I just cannot physically seat the riser cable firmly and correctly into the motherboard because the GPU's are just too fat and push the connections down at too great an angle. So the only other open and usable slot on the board is PCIeX4_1. I mounted the drive onto the expansion card and inserted it into PCIeX4_1, and here is where the questions begin.

Note that I do realize that the drive speed will be slower and limited in that slot, however the purpose of me using this drive is for easy cloning of a backup to a new M.2, not regular use, so it doesn't / shouldn't affect anything other than a slower cloning.

I powered up in the new configuration and the motherboard took forever to POST. I tried it multiple times, changing a setting or two in the BIOS each time. I tried it with AUTO and different GEN#'s for that slot, and I also selected to disable the USB ports shared with it. Every time the POST took at least an extra 2 minutes than normal.

Finally I just booted into Windows after one of the POST delays and to my surprise Windows recognizes the drive just fine! I can read and write to it, there are no drive errors, the driver is installed just fine. Everything is normal. I did not test its speed however, afraid to know right now. So after seeing it was recognized I rebooted, and yet again the motherboard just hangs for a few minutes.

I shut it all down then, removed the new card and then powered back up, and without the card it starts up without a glitch, no POST delay. I just don't get it, can anyone tell me why is the system hanging on POST with the card in that slot?


TLDR:
RVE10 takes too long to POST with an M.2 adapter card (with drive) in slot PCIeX4_1, yet there are no apparent errors. Why?