Computer won't recognize all my memory

[ricoman]

I had 3x2 module for a yr. working fine and added another 3x2 module today but the system only recognizes 8gb of the 12. Though I built this system, I am not real computer geek or expert, just an average enthusiast. Not much knowledge of bios etc. What can I do to check/fix the situation before I RMA? I am not totally sure there is anything wrong with the memory and need to trouble shoot to make sure, it could just be a setting or something. Thanks
PS: see my profile for system particulars. And yes I know, I don't need 12 gb ram, it was on sale cheap and I couldn't resist.

[Bonie81]

if its not mb problem or OS limitation, it is time to update BIOS, flash ROM.

[intracube]

What's the exact type of modules you have?

Have you read through the manual for your motherboard? I've just checked online, and there are a number of constraints listed in section 2.4.2, for example:

Type of modules allowed:
1GB and 2GB unbuffered and non-ECC DDR3 DIMMs

You can only have one X.M.P or DDR3-1600 module per channel.

DIMMs with voltage requirements over 1.65V may damage the CPU.

Also the order of the modules in the sockets (A1,A2,B1,B2,C1,C2) can matter.

[ricoman]

I had 3x2 gb Corsair XMS3 DDR3 1333 in slots A2,B2,C2 which were running fine. I added 3 more modules of the same in the open slots. Only 8 gb are recognized. Belarc advisor says that slots Dimm2 & Dimm3 (B1 & B2) are empty. I never touched B2 which confuses me. Any ideas?

[intracube]

I had 3x2 gb Corsair XMS3 DDR3 1333

There are quite a few memory kits listed on the Corsair site with those features. The following ones mention XMP which *might* be causing you problems:
(TR3X6G1600C8,TR3X6G1600C9,CMX6GX3M3C1600C7,TR3X6G 1600C8D,
CMX6GX3M3A1600C9,CMX6GX3M3A1333C8,TR3X6G1333C7)
http://www.corsair.com/products/xms3/default.aspx
Are you sure you've got *exactly* the same DIMMs?

in slots A2,B2,C2 which were running fine.

The manual suggests the first 3 modules should go in A1,B1,C1

Have you tried the 3 new modules in A1,B1,C1 (with the original ones taken out)?

Not sure if you're already aware - but you should always earth yourself (ideally with a wrist strap) before touching the modules. Memory can be damaged by static electricity.

[ricoman]

They're all the same TR3x6G1333C9. When I put the original 3 in, they had to go in A2,B2,C2. I have not tried taking the originals out and inserting the new ones. I'll try it tomorrow. Yes, I use wrist straps.

[ricoman]

Update: I switched the 3 new memory modules to slots that I know work and all seems OK. Show fine in System and Belarc. Searched the web for more info and slightly jacked up the voltage on the bios; Dram bus voltage = 1.64v, QPI/Dram voltage max = 1.35v. Still no luck. From what I have read, this is a common problem x58 mobo and i7 processor HTF do I fix it??? Going nuts at this point. I hate effin computers!!!

[intracube]

What version of Windows 7 have you got?

Your profile says Win 7 Bus. (I assume to mean Business) but I can't find an official release of Windows called that. If you had Windows 7 Basic, it's limited to 8GB for the 64bit version. See:
http://en.wikipedia.org/wiki/Windows_7#Physical_memory_limits
http://msdn.microsoft.com/en-us/library/aa366778%28VS.85%29.aspx#physical_memory_limits_windows_7

[ricoman]

What version of Windows 7 have you got?

Your profile says Win 7 Bus. (I assume to mean Business) but I can't find an official release of Windows called that. If you had Windows 7 Basic, it's limited to 8GB for the 64bit version. See:
http://en.wikipedia.org/wiki/Windows_7#Physical_memory_limits
http://msdn.microsoft.com/en-us/library/aa366778%28VS.85%29.aspx#physical_memory_limits_windows_7

Sorry, was Vista Bus. with upgrade to 7 Pro. So, it's W7 Pro.

update: updated bios, still no joy!