@EMC2
The voltage on Vmem when you remove AC and then re-apply is caused by the way one of the ICs initializes at power up (along with how it's used). The actual value depends on your settings (it can come up as low as 2.45V).
Sure, doesn't mean that I agree with their HW design. It is simple enough to have circuitry that keeps components in states you want them to be in - without having software to actually do it. Obviously the shutdown code does it - there is 0V on Vdimm. There should just as well be 0V on Vdimm when you plug the AC cord in the back of the machine.

Anwyay, I hope DFI look into turning the Vdimm voltage up to the CMOS specified value before trying to detect the RAM.