MSI Z370 - top PCIe 3.0 x16 slot stopped working

[pc-freak]

Hi, I built my brother a new PC few months ago with all new parts except the GPU and PSU.
The PC stopped sending video signal yesterday.

Specs:
CPU: Intel - Core i5-8600K 3.6GHz 6-Core Processor
CPU Cooler: CRYORIG H7
Motherboard: MSI - Z370 GAMING PLUS ATX LGA1151 Motherboard
Memory: G.Skill - Ripjaws V Series 16GB (2 x 8GB) DDR4-3200 Memory
Power Supply: XFX 650W 80+ Bronze Certified Semi-Modular ATX Power Supply
Video Card: Nvidia GTX 1060 6GB

On board graphics work! In bios, the GPU is not recognized in the top PCI slot, while in the bottom PCI it is (and works fine)

I did I a lot of troubleshooting:

1. Installed the GPU in the second (bottom) slot - SUCCESS ( worked )
2. Installed the GPU in a completely different PC - SUCCESS ( worked )
3. Installed the GPU back in the top PCI slot w/ a completely different ( 600w ) PSU - FAIL ( original problem )

This way I have concluded that the PSU and the GPU work fine.

The bios has not been updated as far as I know.
Do MSI boards automatically update bios? Does that even exist?

I think the motherboard is faulty.

I believe the best thing to do now would be to return the motherboard and get a new one and hope its not the issue with the CPU...

What do you think about this? What is defective? Could CPU be an issue? Have you ever heard of or encountered this problem?

 

[jay32267]

"Do MSI boards automatically update bios? Does that even exist?"
I've never heard of that.

"I think the motherboard is faulty."
So do I.

"I believe the best thing to do now would be to return the motherboard and get a new one and hope its not the issue with the CPU..."
I agree and I tend to not think the problem is much more likely to be MB related.

I've had slots go bad.
They do go bad on occasion and basically the symptoms are what you describe.