New build problems

[Quarrels]

Hello, i just recently bought a new mobo for my system to upgrade to a new processor and i am hoping you guys can help with some problems. First and most importantly these are my specs:

Gigabyte 990fxa-ud3 mobo
Amd FX-8120 CPU O.C. to 4 ghz
8gb 1333 9-9-9-24 AMD entertainment edition ram <----- Where the first problem is
1tb WD caviar green HDD (recognized)
500 gb seagate HDD (OS Drive - recognized)
500 gb seagate HDD (shown in disk manager but not in my computer and unable to access)
160 gb wd HDD (very old, original os drive, i dont really care if this one works)
AMD 6870 by HIS
750 watt PSU Kingwin


So as you can see from above my biggest problem is the ram, my system tells me that i have only 6gb installed and only 3.86gb usable. I have the modules in the closest slot to the cpu and then skip a slot and the second module is in the 3rd from the cpu slot ( I have tried the same spacing from the other side but no difference). The second problem is that those 2 hdd's are not being recognized, or at least I cant use them. They are in disk manager and they are labeled as " Healthy (system, active, primary partition). Now this drive has not been reformated since I reinstalled windows (7 pro) for my new hardware but if its possible I'd like not to because it has my steam data on it.

Thanks for any help, Quarrels

 

[Quarrels]

Edit: So I've figured out the hard drive problem and for anyone with this issue in the future all you have to do is go into disk manager, right click on the partition and go into the change drive letter and paths option, choose a drive letter and press OK. Man I feel like an idiot for that one but I still haven't figured out the ram issue, also i forgot to mention earlier that the ram displays as 8gb in the BIOS, so I don't think that the ram itself is the problem.