Question PC refuses to POST when GPU is in PCIE 4.0 x16 slot, but works in a lower bandwidth slot ?

[hyperix]

I've encountered a rather weird problem.

So, I've finally received my new PC parts, I have first made a test bench the moment it all arrived. And when I inserted the GPU into the PCIE x16 slot, it didn't POST...

The motherboard showed me a white LED near the VGA label.

I almost thought the graphics card was dead but when I put the GPU into the lower x16 slot with way less bandwidth, for some mysterious reason the PC decided to POST successfully.

Checked GPU-Z, and it shows that the GPU is running in x4 mode, but supports x16 3.0 mode? What the heck?

I've tried changing the slot's mode to Gen3, assuming my GPU just couldn't work with Gen4 mode. But nope! It just didn't post again!

I'm not sure if it's a defective motherboard or just the GPU's fault, but it's all new parts except for the GPU and RAM!

Here's my specs:

MBD: MSI MPG B550 Gaming Plus
CPU: Ryzen 7 5700X
GPU: Asus Rog Strix RX 570 OC 8GB
RAM: 16GB DDR4 2400MHz

 

[helpstar]

update the bios of the motherboard
which m2 ssd are you using?
where is it connected? which slot?

 

[hyperix]

which m2 ssd are you using?

I don't have an M.2 SSD. It's a SATA III SSD

where is it connected? which slot?

you mean the gpu or the ssd? if you mean the gpu, right now it's in the lower x16 slot, since this motherboard has 2 x16 slots, the one with steel armor and the one below it

update the bios of the motherboard

i might try that but im not really sure.

 

[SkyNetRising]

Checked GPU-Z, and it shows that the GPU is running in x4 mode, but supports x16 3.0 mode? What the heck?

That just means - the card is x16 and it is placed into x4 slot.
Second x16 slot on motherboard electrically is only x4.

I've tried changing the slot's mode to Gen3, assuming my GPU just couldn't work with Gen4 mode. But nope! It just didn't post again!

Try forcing it into PCIE 2.0 mode.
Are you using any PCIE riser cables?

 

[hyperix]

Are you using any PCIE riser cables?

no i put the GPU straight into the mobo. I even double checked to see if it's seated correctly.

Try forcing it into PCIE 2.0 mode.

tried that before, still didn't post unfortunately.