PC doesnt boots when 2x gen 4 NVME ssd are installed

GeeBee007

GeeBee007

Disciple
So i have a Asus x570 prime pro and today i was going to replace my gen 3 ssd with 2x gen 4 ones.
But when i install a gen 4 ssd on the upper slot.The pc doesnt boots and gets stuck on VGA boot light...I thought maybe there is some lanes sharing problem between the top M2 slot and gpu so i disabled the Rebar memory in BIOS but still the same....both gen 4 ssd work in bottom slot and it also works when gen 3 ssd on upper slot
On setting the top M2 slot to forced gen 3 in BIOS seems to work but then both gen 4 slots should work.
BIOS updated to latest
 
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There shouldn't be any lanes shared or conflicting between the m.2 and PCIe slots. The top m.2 is directly from the CPU, the bottom is through the chipset though both are Gen4. The two top slots are from the CPU and can be in either x16 or x8/x8 configuration. The bottom PCIe slot is Gen4 x4.

Take a closer look at the top m.2 connector on the motherboard, it may have dust and may need to be cleaned with isopropyl alcohol on a cotton swab. Same with the gold contacts on the SSD. I struggled with this for days before noticing a small spec of dust on the m.2 connector.

Also try a BIOS reset, sometimes boards need a cmos clear to be done when switching between Gen3 and Gen4 SSD's, usually with Ryzen 5000 series and B550/X570 motherboards.
 
www.bleepingcomputer.com

Asus X570 pro 2nd m.2 nvme slot - Internal Hardware

Asus X570 pro 2nd m.2 nvme slot - posted in Internal Hardware: Asus X570 pro 2nd m.2 nvme slot. I filled up m.2 1 next to chipset. This is right where my 3070 is. Running fast even though gen 3. There is an lower m.2 gen 2 nvme slot 2nd slot that acording to manual will run at gen 4x4 speeds...
www.bleepingcomputer.com www.bleepingcomputer.com

You can see a similar issue being discussed here. The OP there was also told by Asus support that the second slot will have only one lane when using the external GPU. It doesn't make a lot of sense with respect to how the slots are wired, but it seems there is probably some issue at Asus' end.
 
GeeBee007 said:
So i have a Asus x570 prime pro and today i was going to replace my gen 3 ssd with 2x gen 4 ones.
But when i install a gen 4 ssd on the upper slot.The pc doesnt boots and gets stuck on VGA boot light...I thought maybe there is some lanes sharing problem between the top M2 slot and gpu so i disabled the Rebar memory in BIOS but still the same....both gen 4 ssd work in bottom slot and it also works when gen 3 ssd on upper slot
On setting the top M2 slot to forced gen 3 in BIOS seems to work but then both gen 4 slots should work.
BIOS updated to latest
Click to expand...
Look at the motherboard manual it is definitely related to PCIE lanes allocation you can maybe get by running the top ones in gen 3 since it is stopping at vga light it definitely means it cycling through the POST so not a CPU or memory issue.

Make a bootable Linux preferably CentOS distro and run a device check to see the iommu groups that will you to identify how each slot is wired.
 
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