Question Two issues with PC

[Axis192]

Hello!

I am facing an issue with a PC. The big issue with the PC is that a drink was inadvertently spilt on it. This issue made the fans 'rev' up just before I was able to kill power and remove the CMOS.

I reconnected up the PC after a few days' drying and it seems the GPU died; the exact issue is that the GPU, when NOT plugged in to power, allows the system to start booting up but no image (as CPU doesn't have an IGPU either ). As soon as I connect power to the GPU (6650 xt) it point blank refuses to switch on.

I have now replaced the GPU with a spare 1080 for now - the PC is on right now and I am typing this out on it. However, there are still two problems with the machine:

1. As soon as the PC 'sleeps' - it refuses to come back on. If I hold then press the power button to turn it off and on I get nothing in terms of image at all. The only way to get the PC to come back on is to switch it off at the wall and then turn it on which shows the BIOS splash screen and it proceeds to boot. Otherwise I get no response at all.
2. Possibly related to the first issue, prior to this drink spillage, the computer would not come back on when it goes to 'sleep'. What I mean by this is, when it was left to 'sleep', the computer would just every 10 mins go back to boot and would keep restarting every 10 mins. Windows Event Viewer shows this as a 'Cache Hierarchy Error'.

I am confident that this is not an issue with the following:-

1. SSD - I have replaced this.
2. Cooling/cooler - the item is not thermal throttling and I have re-done the thermal paste yesterday.
3. Case - PC was rebuilt inside of a different case (due to personal preference).
4. GPU - I have now tried three GPUs (6600xt which died for separate issues, 6650xt water damaged and my current 1080).

This points to one of 4 things:

1. RAM
2. CPU
3. Motherboard
4. PSU

I am unsure how I can get to the bottom of this. I bought the CPU and motherboard as part of a bundle which remain in warranty just about.

The PSU is a very good model and I have memtested the RAM which brings no issues. I have tried to clear CMOS to no avail. I have tried a fresh Windows install as well.

My questions are:

1. How can I figure out what is at fault?
2. What do you think is the most likely culprit? I am very sure it is the CPU and/or motherboard at fault which, if confirmed, I can RMA. But I am slightly hesitant to return these for two weeks for them to say 'there is no issue'.
3. Re the 6650xt, is there any 'salvaging' this or am I just getting rid of it for parts/'scrap'?

Specs:

5600x AMD - Hyper 212 EVO cooler
NVIDIA 1080 - MSI Twin FROZR edition.
2x 8GB DDR4 sticks of CRUCIAL RAM - Tried with XMP off and on.
B560M-DS3H motherboard
SU630 SATA SSD (former) and SN850X NVME (current) - tried switching these out
CX750M Modular PSU

Any advice is much appreciated.

Thank you.