After learning that the 3612QE itself supports ECC RAM in contrast to the stock CPU options and that the QM77 chipset also does, I purchased a DDR3 SODIMM with unbuffered ECC. I have not been aware of any other attempts to test this combination.
The machine did not POST and did not produce any beep codes. Absolutely no response to any input aside from shutting down when briefly holding the power button. Everything returned to normal upon putting the original RAM back.
I suspect the BIOS lacks support, but whether this changes with coreboot remains unknown to me, at least until I learn how to prepare and flash coreboot.
This is purely an exercise in curiosity.
I know my P1 gen 4 could be optioned for ECC ram, but that was if you bought the xeon version instead of the i9. But I thought ECC on laptops started with DDR4