Having problems with motherboard/CPU

[Reemas]

Hi everyone!

I recently submitted both my CPU and motherboard for RMA. I received a sealed box CPU from AMD, and an open box/used motherboard from ASRock. I am having some weird issues with this new setup. I am inclined to believe the problems are caused by the motherboard since it isn't new, but still I'd like to verify this before going through the annoying RMA process again.

 

Specs:

1. Ryzen 7600x
2. ASRock B650E Steel Legend
3. Gigabyte 6800 XT
4. G.Skill ram(f5-6000j3238f16gx2-tz5nr)
5. NZXT C750 Gold

Issues:

1. Primary pcie slot is stuck at pcie4 x8 under full load, even though I'm only using 1 nvme slot and there is no lane sharing. It used to work at x16 on my original setup.

2. System doesn't post if I enable EXPO, even though my RAM is on the motherboard support list and was also working with my original setup.

3. Sometimes the system boots into windows but my display stays blank.

I have already tried re seating the RAM and GPU.

Please help me identify which part might be causing the issues.

Also, is it a usual practice to provide used parts under RMA? This was my first time claiming warranty.

[OddOod]

Welcome to the forums!
Did you update the BIOS?
Have you tried a new display cable? Sometimes they die for literally no reason.
When it fails to POST, there should be some LEDs on the mogo that light up telling you what step it's hanging on. Look above the 24pin and to the right of the RAM. Which light is lit? 

[Reemas]

Turns out it was the motherboard after all. Wasted hours off troubleshooting and then gave the board for RMA again. So disappointed with asrock, clearly they don't inspect refurbished boards before sending them out to the customer