Windows 7: 16 GB RAM - 15.7 GB usable 4GB RAM 2.7 GB usable ???

Hi there
What gives

I uppped the memory of an ASUS Motherboard to 16 GB - no extra video card or whatever from 4GB --running Windows 7 X-64 Enterprise version (approx equiv to Windows 7 Ultimate). 4GB memory chips are CHEEEEEEEAP currently so why not upgrade !!.

I now get in the properties Usable memory 15.7GB (installed memory 16 GB). Fine by me.

When I had 4 GB installed the memory status showed 4GB of which 2.7GB was usable.

Why the difference in usable memory -- the BIOS or internal video hasn't changed.

Cheers
jimbo

I would go into Task Manager, than Resource Monitor, then the memory tab and see what's up. I wouldn't expect you would see the difference.

Since you asked the question.
#1). Because you likely won't need it, and performance won't change. Unless you run concurrent virtual machines with large amounts of RAM.
#2). Filling up RAM slots can make things like overclocking more of a challenge.