Quote Originally Posted by lastof View Post
Quote Originally Posted by illutian View Post

I'm currently dealing with this. Of the 12GB (4GB x 3) I have installed I now can only use 7.99GB. Note how I said "now". I use to have the full 12GB "usable", but now it's only 7.99 flagged as "useable" under 'System', but Windows does see the full 12GB. BIOS only sees ~8GB.
...It appears my DIMM 3,4 banks have died (spare RAM 6GB [2GB x 3], so total of 18GB, doesn't show the 2GB in DIMM 4 either)

Not too bad I guess for a MOBO from 2009, that's been run for 14hrs a day
Illution, it may be different for your system, or this may not be the case anymore (I do not build machines anymore, so my suggestion is probably an outdated one), but it's worth a mention I guess -

I know you mentioned having 4 DIMM banks, and if I understood you correctly, it seems as if your system wouldn't recognize the RAM in bank 3, or 4.

It used to be that you had to add RAM in pairs - ie., if banks 1 & 2 are being used, and you decided to add a stick to bank 3, bank 4 would also have to be occupied for banks 3 & 4 to be utilized properly. Is it possible that this could be the source of your problem?

Like I said, I haven't fiddled with a motherboard for some years now, but I thought I might bring it to your attention if there was a possibility that it might help...
Ah, I should have elaborated. And it appears the OP doesn't have the same issue. After re-reading their post they state, as least in my understanding, that the BIOS sees the full amount of RAM.

So I'll wrap the below in 'Quote' in case anyone stumbles upon this topic, as I did, searching for the reason their system has the similar issue.

For Future Readers: If your BIOS does not see the RAM there's something wrong with the hardware, not the OS.

For the OP: No clue why it's reserved that much, seeing as you appear to have dedicated Video memory (256MB?). My other Win8.1 system, that doesn't have bad RAM slots, only has 2MB of the 6GB reserved for hardware; it also has a dedicated video card with dedicated video RAM.

Since you didn't post it...post a screenshot of the 'System' (right click Windows "start button" -> System; or search for 'system'). It'll probably say something like "Installed memory (RAM): 4.0 GB (1.78 GB usable)".

My system has 6 DIMM slots and is Triple Channel. . The 'center bank's, DIMM 3 and DIMM4, are not recognized in the BIOS. But they are 'seen' by the system, however the memory located in those banks are flagged as "Hardware Reserved". I'm assuming this is done to prevent the OS or applications from trying to write to those address blocks, erroring out (because the banks are faulty), and causing a BSoD or data lose prior to being written to the harddrive.

I've tested all three RAM Sticks in DIMM1 (aka DIMM0 in some software) and all the stick check out both in the BIOS (sees all 4GB of each stick) and in MemTest86.

Same goes for all six of the RAM I tried (2 sets; (1) 6GB, (1) 12GB). DIMM1,2,5,6 all detect the sticks in BIOS and MemTest86. Anything put into DIMM3,4 are not seen in the BIOS or in MemTest86.