Bad CPU or motherboard?

[Betelgeuse]

Been using Asus Rampage V Extreme for 2 years almost with no issues, with a 5960X CPU, no overclock. Today while playing Doom the PC froze. After doing extensive troubleshooting it seems that putting a RAM stick into the rightmost red slot causes lockups at random, even in BIOS. Putting the same stick into other slots causes no problems, populating 3 out of 4 slots with RAM causes no issues as long as the rightmost red slot is left empty. If I put a stick into that slot, either alone or with other RAM system becomes unstable. Updated BIOS as well, etc., no effect (changed RAM timings as well). Question is, without access to another CPU is there a way to determine whether it is the motherboard or CPU that is faulty?

[MeanMachine]

Run Memtest86+ from a USB stick to check all your DIMMs.

I assume you have checked that your DIMMs are listed on the ASUS QVL.?
Also that Primary Timings and voltage set correctly in Bios.?

Check the DIMM slot that there is no contamination. Clean out the slot with Compressed air from a canister and only do this with PSU turned off.
If still no success then you will have to benchtest your system and at the same time check for any bent pins in the CPU socket.(probably not if its been running for two years OK)
Start in a minimalist state, then add one hardware component at a time whilst observing your Qcode leds for errors.
Unfortunately there is no way to really determine if its the MB or CPU with out swapping them out to test.

[Bahz]

I would recommend reseating your CPU and yes a defective CPU can cause something like this. Try to also loosen the pressure on the your heatsink to reduce pressure on the CPU socket.

[Betelgeuse]

The memory is qualified. The system has not been touched in a long time, it just suddenly started to happen for no apparent reason. I haven't touched the CPU nor RAM since I built this system in late 2014. The only thing I have not tried is to re-seat the CPU. I'll try that tonight and see what happens.

[Betelgeuse]

Reseated the CPU and the problem got worse, the computer would not POST with a stick in the rightmost slot and even when using MEM OK button it would only detect 24GB out of 32GB installed. Intel is already sending me a new CPU so I'll try that and then move onto the motherboard if the new CPU shows same problems.

[Betelgeuse]

Tested the new CPU and the same problem, bad board I guess... sigh..

[MeanMachine]

Tested the new CPU and the same problem, bad board I guess... sigh..

Did you inspect the MB CPU socket for bent pins, use a magnifier and look for obvious differences in alignment or pins bent down.
If you do, you can carefully bend them back with a toothpick. Do not return the MB with bent pins as this will void your Warranty.

[Betelgeuse]

Did you inspect the MB CPU socket for bent pins, use a magnifier and look for obvious differences in alignment or pins bent down.
If you do, you can carefully bend them back with a toothpick. Do not return the MB with bent pins as this will void your Warranty.

Yes, I looked carefully at the socket and did not see anything that indicated damage to the pins. They all looked identical.

[FireRx]

RMA the motherboard. better off replacing it than to possibly damage the new CPU.