my computer has 16GB of RAM, but only 7.99GB is usable.
 
I have:

• EVGA P55 LE 123-LF-E653-KR LGA1156 Intel P55 ATX Intel Motherboard

• (16GB total, 4 cards) CORSAIR Vengeance 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model CML8GX3M2A1600C9B

• Windows 7 - 64bit
• I checked BIOS, and it only shows 8084MB.
• I tried to disable memory remapping, but i got less available.
  

I flashed the bios, and downloaded all driver & firmware updates.
Can anyone tell me how to get the computer to use all 16GB of RAM?
 
thanks!
 
D

I did test each stick separately. they all read properly. (i pulled them all out and re-seated each one, testing as I went)
 
what is IGP?

VTT on lynnfield is a default of 1.1v, max is 1.4v and should not be overclocked more than a extra 0.5v.
So basically check your voltages.

VTT is also known as qpi/dram, qpi/vtt or imc but this depends on the manufacturer.
 
Look for your dram/vdimm voltage, then compare that to your vtt voltage. Remember your dram voltage should not be more than the 0.5v above the VTT that i mentioned. VTT should be 1.1 so the threshold of 0.5 = 1.6v - this the highest it should be, unless you are upping the VTT as well.
I hope where i am going with this is the cause of your problem.

As odd as it sounds,  do you have your CPU cooler on too tight?  Sometimes when things are bending in ways that they should not be, you will have memory issues (Either it won't post, or it won't detect it all). 
 
Since you've tried all of the easy stuff,  I would take off your CPU cooler, reseat the processor, and when putting the cooler back on make sure it's not on too tight.  No bending!
 
Then reseat the ram and see what happens!
 
(Edited for punctuation)

Have you tried default settings on everything and attempted to raise just the cpu pll voltage?
Have you oc'd the cpu?

this is what i see in BIOS
 
bootup CPU vcore - auto
current dimm voltage 1.50v
dimm vll - auto
current VTT 1.05v
bootup cpu vtt- auto
eventual cpu vtt- auto
current pch voltage 1.050v
pch- auto
cpu pll- auto ( I tried changing this to 1.55 & 1.65, no change in memory)

HOLY CRAP!
 
I reseated my CPU (it was actually kinda loose, as opposed to being overtightened) and now I have 16GB of RAM and 14GB usable!
 
Do you think I should still oc the cpu?

Only oc if you need to, really depends on what your whole setup is and what your expectations are in terms of performance, also it can eliminate any potential bottleneck. Also ipwnnoobsirl should be thanked. Not sure about the 2gb, must be reserved for something.

Also,  did you reseat the ram at the same time as the processor?    Just trying to cover all our bases.  

I think you have issues with either the memory or the slots on your motherboard. 
 
Can you find a way to download this and put it on a CD?  It's a free program that tests your memory.  If your memory is bad,  it can definately cause what you are describing.
 
http://www.memtest86.com/
 
You will probably need to test each stick individually and see which one is the bad one.  It COULD be the SSD, and anything is possible, but if you're having issues with your memory anyway, I'm going to guess that the memory is the problem.   
 
Take all out but one,  see if it will boot.  If it does, try to burn that program onto a CD, restart and boot from the CD, and let it test the memory.  If that stick passes.. shut down, take out that stick and set it in a "good" pile, pick another, and test that one.  Hopefully you'll find the bad one.  If there is no bad one, it could be one of the slots, and you can either not use that slot or replace the motherboard.
 
Either way, you have a little work ahead of you if you want to fix this.  Let me know if you have any issues and I'll try to help you as best I can. 
 
Good luck! 

When you say that you tested them earlier, did you use a program to test the memory, or just put them in one at a time to see if it would boot?  A bad stick can still boot,  but then bluescreen you later.  I would run the program on each individual stick to see if any errors pop up. 
 
The SSD thing and motherboard is up to you, but I'd probably test the memory before you go full nuclear on this system.  Replacing RAM is a lot cheaper than other parts.  I know a lot of people have had issues with the early generations of OCZ SSD's.  I have used Intel SSD's, and currently I use a Crucial M4, and it has been rock solid.
 
When did you first install the SSD?  Did all of these problems start when you installed it, or was it doing the memory thing before then?

Have you set the memory timings and voltages manually in the bios before you test them.
not setting the memory right can also cause the issues. also on you ssd make sure you test your ssd
and due a secure erase of the ssd and a firmware up date on the ssd then reinstall your os.
 
 
http://howto.cnet.com/8301-11310_39-20115106-285/how-to-securely-erase-an-ssd-drive/