Ok so I took the mobo, CPU and cooler to a local PC repair place.
They said it worked when they put it all together with their own test hardware, except for the integrated graphics. So their conclusion was the GPU causing trouble.
Doesn't really make sense to me why GPU problems would cause the DRAM LED to light, but what do I know.
After I took it home and put everything back together, everything seems to be working.
I'll be getting back to work on the one commission I desperately need to make progress on.
Thanks all who gave your advice and well wishes.