How do I set number of processors in command prompt?

I have 16 gigs across 4 DIMMs. Recently windows started doing the (12gb usable) thing. Yes they all work and are all matching sticks, and no I haven't changed any timings or clocks. Using win7 64... 2 months ago it was fine and saw all 16 as usable. I noticed all the windows 7 computers at work are doing the same, so I'm not sure what's going on there but it seems to be common. I know some cards require their own dimm to run properly but considering my 1080 was in there before it started doing this, I had a hunch it might be a bug. So I went to msconfig, boot tab, and checked the maximum memory box, where it automatically set it to 16gigs. I was going to reboot and see if that worked, but I noticed the number of processors checkbox to the left of that, and decided to tell it I had 6 (because I had 6 cores), not sure what I was expecting there.

Well now she blue screens even on boot into safe mode. Now I'm kind of screwed. I can get startup repair to come up and can bring up command prompt. I know there's a way to tell it to go back to a single processor, or deactivate those check boxes, but I don't know the commands for that. Does anyone here know?

I can see it in bcdedit but I don't know the command or syntax to tell it to set the 6 to a 1.

Update- I can change it with "bcdedit /set numproc 1" but it refuses to stick. I reboot and same thing. Back into cmd and it's back at 6?

Images on following post link.