Motherboard not detecting all of my RAM?!?!?

Hardware Hub Motherboards
1

Hi, I have an EVGA x58 132-BL-E758-A1 up until now I have been using 6GB (Triple Channel) Corsair Dominator 1600mhz 8-8-8-24 and the motherboard is detecting all of them in their respective slots. A week or so ago some Geil Dragon 16GB (Dual Channel) 1600mhz 11-11-11-28 went on sale so I decided to get it because it was so cheap.

So I put in the new RAM and notice that it is only dececting 8GB, so I double checked that they were in the correct RAM slots for dual channel and still nothing, Tried them in a number of different combinations, only 8gb showed up. Tried them both one at a time and they worked fine. I took the RAM around a friends house and it worked straight away on his, the full 16GB was shown in the BIOS and in Windows (He is using a Dual Channel motherboard). So I get home and put the RAM back into my motherboard to see if it was just me being an idiot and sure enough both sticks were being detecded in Windows and the BIOS, even though I put them in the same slots with the same settings as before.

That was all a couple of weeks ago now and up until today all 16GB has been usable and been detected in the BIOS and in Windows. I turned my pc on this morning and now it is only showing 8GB in the BIOS and in Windows. I have tried multiple reboots and it is still only detecting 8GB.

I have changed nothing to make it stop being detected and the LED's that are on the RAM modules are glowing their normal colour. Also a wierd thing is that in CPU-Z it is detecting all 16gb, here is a screenshot of CPU-Z  http://i.imgur.com/YllIbtR.png  and here is a screenshot of Windows  http://i.imgur.com/xW9fumx.png

The only thing I can think to try is updating my motherboards BIOS but surley as they have been working for a couple of weeks now that can't help anything?

Any suggestions? 

p.s. Sorry about the wall of text

p.s.s System Specs:

Windows 7 Professional 64-bit

Core i7 920 @ stock

EVGA x58 132-BL-E758-A1

16GB Geil Dragon

EVGA GTX 470 x2 in SLi

Corsair HX1000

various hard drives

2

Have you inspected the sockets of the motherboard?  It sounds like their efficiency is next to none.

3

Not a close inspection but they looked fine from a distance, when I put the 6GB Corsair kit back in, it detects all 6GB so I personally dont think its the motherboard but then again the RAM works in my friends PC so I dunno if it is something wrong with windows or a BIOS setting? The RAM is being detected by CPU-Z so that makes me think that it is a Windows problem?

4

Try updating the bios.  Have you checked to see if there is a dual/triple channel ram option in the bios settings somewhere? 

5

If you currently have a total of 5 dimms especially mix densities you are asking for issues especially with the memory controller on X58 and the compatibility issues that can occur on EVGA boards. That being noted one of the most consistent issues at causing memory initialization issues is stress to the traces and PCB board.

If you are currently using a cooler which has a back plate consider loosening it slightly and reseating the cpu. Additionally if you want to try something a little extra CLR the CMOS while the CPU is out of the socket. This can help to eliminate stuck MRC values which could impact new memory from correctly being initialized.

As also noted you should update your bios to the latest version and load bios defaults. the new modules you purchased have different sub timings and possible voltages. Additionally the MRC ( memory code ) that initialization each times the board boosts could be having issues due to the difference in  memory.

I would recommend you consider manually setting the memory divider to 1333 with a CAS of 9 or 10 to ensure that all the dimms generally initialize at the same values. This will help in post initialization and hopefully allow for complete memory allocation detection.

Hope this helps. Please enjoy the rest of your day.