Question I think my new MSI B550-A PRO might be dead, how can I tell?

Aug 28, 2021
I recently put together most of a new pc (MSI B550-A Pro, Ryzen 9 5900X, Noctua NH-U12S, 16GB Corsair Vengeance 3200 DDR4, Corsair RM650) whilst I wait for GPU prices to drop, and I've encountered an issue with my old card (EVGA Geforce gtx 1060) on my new mobo.

The fans spin for about half a second on and off for several seconds then stop, and repeat that endlessly, as if the card is not getting enough power. The debug LED on the mobo remains constantly lit at VGA. The odd thing is that this happens on my new mobo with both my new and old PSU's, but also when the GPU is not attached to the PSU.

I know that the card still spins fine and that the PSU's are not the issue, because both of my PSU's work with the card on my old mobo without issue.

I've tried resetting the BIOS. There is 100% no wire or obstruction preventing the fan from spinning, and I know for a fact that my GPU is not faulty. I've tried using both PCIe slots on my mobo with both PSU's and there's no change.

Am I missing something super obvious or is my mobo dead?