No video out with GPU in x16 slot (solved)

[SJones]

I have recently got a asrock x470 master sli board along with a new 5950x and got it up and running easily enough.
I had left it on overnight and by the morning it looked as if it had crashed - no display output and didn't see it on the network (could of just been a display issue and not a full crash)
I had the GPU in pcie slot 4 (second x16 slot) after rebooting the pc I still got no video out yet boots into windows.

If I put the GPU in any of the pcie x1 slot, I get video out again. However putting it into the x16 slot I don't get any video out.

I then got an old pcie x1 extension cable - tested it first in the x1 slot and as expected I got video output - using the same extender in either of the x16 slots (so still running on x1) again no video out.

I went through the bios and changed the target pcie gen speed to see if it made a difference but nope.

The fact it initially worked and then stopped (not even getting post screen) should mean the bios shouldn't be an issue - I updated it to the latest anyway to ensure the 5950x worked with it and reset it to defaults amid my testing.

Any ideas on what could be wrong and any more diagnostics I could do?

I'm sure I read that some pcie lanes are on the CPU and some are on the chipset - could this be the issue?

[SJones]

Welp... Figured it out, I was reluctant to pull the CPU as I was out of thermal compound, but more research pointed to the x16 slot being directly on the CPU.

 

Pulled it in the end and my first thought... Thermal paste application was the best I had ever done, full coverage with minimal over the edge.

 

Had a whiff of warm electrical smell, turned it over and CPU has burn marks...!