Something to think about:
The POST card displays the values in hex. 3P is not a valid hex value. If I stand on my head, it looks like dE, which is a valid hex value. Unfortunately, DE is not a publicly documented standard AMI BIOS code. It may be a custom MSI specific or chipset specific code that is not publicly documented.
The Dx series of POST codes relate to the bootblock initialization checkpoints. The bootblock initialization code sets up the chipset, memory and other components before system memory is available. So I think that would point to a motherboard component or chipset failure, or even the RAM, as it gets initialized during this part of POST. I would try swapping the RAM if you have a comparable module available, and then retest.
Hope some of that is useful.
~Colin