"Hardware Reserved" abnormality

Ok, so I've read over some posts and looked around at some sites talking about "Hardware Reserved" Memory but my problems seems to be a bit unique - but perhaps not.

I'm not sure what all system specs are relevant to this problem so I'll list the basics
- Dual E5530's (16 threads total)
- 24GB DDR3 Memory (6x4GB)
- Quadro CX Workstation Graphics Card
- Win7 64bit - or course

My system is reading as having 4GB (4105MB to be exact) as "Hardware Reserved". This is only viewable under the Memory tab in the Resources monitor and under the MyComputer preferences where it says 24GB (20 usable). I've read posts where it says that certain hardware such as the graphics card and motherboard (bios) can reserve itself memory, but this just seems like a lot... and it also seems to close to what one stick of memory provides... coincident?

What makes this more unique than other situations I've read, is that when I run MemTest it only sees 20GB and CPU-Z only sees 20GB.

I've physically taken out and re-installed all memory into the motherboard and have also completely reinstalled Win7 from scratch. Problem is 100% the same throughout so perhaps it really is reserved and working properly? But if not, I want to know cuz i often max out my memory with the new 64bit After Effects CS5 so I could use any extra memory I can get - unfortunately I can ill afford another $1,400 to install another 24GB just yet.