Motherboard and Windows not showing all installed ram.

[Q51]

I have been having some issues with ram in my recently assembled computer, first it was compatibility and now I don't know what it doesn't like. I have experience with hardware (Mostly budget) but this is the first system that I was able to put real money into.

Anyway hears the important info,

Motherboard: GIGABYTE G1.Sniper LGA 1366 Intel X58
CPU: i7 920
RAM: G.SKILL Ripjaws X Series 8GB (2 x 4GB) x3
PSU: SeaSonic X Series X-850
GPU: GTX 570 x2
HDD: 7200 rpm 1TB Samsung


As of last night my problem is that in the bios and OS only shows 20 GB of RAM. And inside windows it says that only 16 GB is available, although it thinks there is 20 GB installed. I know the x58 motherboards can be a bit picky and my board is no exception, but I was hoping someone hear might have some ideas that I have missed.

 

[Violator]

First off, what version of windows are you using? Windows 7 x64 for example, only supports more than 16GB of memory if you're using Professional or higher.

 

[Q51]

It is running Windows 7 64-bit ultimate.
I have not made any changes with any settings If that matters. I have never had this much ram in any system I have worked with so this is all new to me.