Asus z170a pciex16 slots not taking x8 cards like the supermicro slg3-2m2 8x nvme (only 4x mode)?

[markm75]

I have the older 6700k with the asus z170a board. I have an m.2 slot filled (i've tried enabled m2 express vs sata express in bios btw, but each time i restart it resets to sata express, unsure what the m2 mode even means, the onboard sata m2 nvme works fine).

So i have 2 nvmes, i put them in the supermicro unit, but each time no matter what slot i use, either the first or 2nd which should be 16x or 8x if both in use, it defaults i think to 4x, as the second drive doesnt show up.

I checked in the bios, there is no toggle to make it force 8x mode that i can see, though there is auto and gen1 through gen3, i have (pretty sure) tried gen 3 forcing with no luck.

Having the card in also causes weird bios loop issues if i try to tap del to enter the bios, it seems to almost reset the initial bios display of data where you tap delete, i had to go into windows and select uefi mode to get around it.
Since usually i cant even get to the bios once the card is in, i cant get in to look at the setting to see if its running at 4x mode or not (obviously is though).

Anyone else ran into this 8x issue with this board and found a fix?
Thanks in advance

 

[toast0]

Your card relies on (passive) pci-e bifurcation. If you can, set your slot to x4/x4 (or x4/x4/x4/x4) in bios (possibly with the card unplugged since it seems to make the system sad). Some boards need a special bios to enable bifurcation, so maybe check asus forums or email support and see.

 

[markm75]

I guess another question is if a riser converter card like this would work on a pciex16 slot or for that matter i guess the pciex1 slot (unsure how it can take a 1x slot and make 4 though) in the z170a
https://www.amazon.com/gp/product/B07B2SWS2D/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Trying to avoid swapping board/cpu for now, just need a way to either free up a slot or two or i guess skip the dual nvme via slots (at least via the same slot).

 

[markm75]

Update, the riser converter/multiplier card worked fine, just not in the pciex16 slot.
When i had it in the pciex16 slot it gave me a b1initializelibrary failed 0xc00000bb error.

i tested this multiplier card with 3 gpus attached and was still able to have two pciex4 ssd nvme cards in the system with no issue (also have a gpu in another slot and will be adding one more gpu to another free slot as a result).