usable RAM mysteriously dropped

[Aaron Hulett]

I think the shared memory setting, if available, would be in the BIOS settings. May be worth a look there to see if you can adjust it.

[Digerati]

Since the amount of shared memory is set in the BIOS, it is not surprising restoring back to a different date didn't change anything.

Edit add: Aaron beat me to it.

[plodr]

shared memory setting, if available

I'm not sure I have this.

Back on 17 Feb., in my first post I stated that I looked over all the options in the BIOS. (I actually did not go into the section about setting up a BIOS password).

I'll have another look to see if I missed it.

[Digerati]

I have often found it easier to download the motherboard manual and search it with Foxit Reader.