12GB RAM installed and only 8GB showing in Windows 7 Ultimate x64

[Guy Robinson]

Good afternoon,

Last summer I custom built a PC and have had it running with 2x2GB RAM since then. I recently purchased 2x4GB RAM in an attempt to boost the total up to 12GB

The RAM I have are as follows:
Original 2x2GB: http://www.corsair.com/en/memory-by-product-family/vengeance/vengeance-4gb-dual-channel-ddr3-memory-kit-cmz4gx3m2a1600c9.html
New 2x4GB: http://www.corsair.com/memory-by-product-family/vengeance/vengeance-low-profile-8gb-dual-channel-ddr3-memory-kit-cml8gx3m2a1600c9.html

I put them all in the mobo and booted up and Windows only found 8GB. I did Mem ok and it was still the same. In Bios it says I only have 8GB Ram except when I go into the advanced options and look at each slot it says there is 4,2,4,2 (12 in total) and CPUID also finds 12GB in the slots.

I have reseated them all and rejigged the order as much as I can (I have to have the low profile RAM first because otherwise my CPU fan gets in the way)

Could it be something to do with the voltage (or something else I don't understand) that means the other 4GB isnt being found? Any help would be greatly appreciated

specs:
Motherboard: ASUS Sabertooth z77
CPU: i7 3770k
Windows 7 Ultimate 64 bit
RAM is specified above

Is there any other info that you may need that could help diagnose the problem?

Thanks a lot,
Guy

 

[n1ghtr4v3n]

in bios, you can limit/unlimit physical memory usage.

here is a thread how to solve it by Microsoft help center. I hope it works for you.

http://support.microsoft.com/kb/978610

 

[Guy Robinson]

in bios, you can limit/unlimit physical memory usage.

here is a thread how to solve it by Microsoft help center. I hope it works for you.

http://support.microsoft.com/kb/978610

In system information it says "Installed memory (RAM): 8.00 GB" rather than "Installed memory (RAM): 12.00 GB (8.00 GB usable)" so the problem is that Windows can't find the other 4GB, not that it's found them but isn't using them

 

[jungle71]

you are better off having a consistency with your ram,unless instability can occur also make sure your rams have equal timings/voltage settings.

opinion -"even if there is 12gb, windows might have only choose two correct ones with equal timings/voltage settings."

 

[Guy Robinson]

you are better off having a consistency with your ram,unless instability can occur also make sure your rams have equal timings/voltage settings.

opinion -"even if there is 12gb, windows might have only choose two correct ones with equal timings/voltage settings."

These are pictures of what CPUID says about the two different types of RAM. The voltages are the same but the frequency, tRAS, tRC and JEDEC #2 values differ. Are these what I need to change in BIOS?

Thanks

 

[n1ghtr4v3n]

the 1st thing i realized is different xmp profiles. are you sure both of them are compatible with your mobo ?

 

[Guy Robinson]

the 1st thing i realized is different xmp profiles. are you sure both of them are compatible with your mobo ?

Yeah, I have had both pairs of RAM working successfully on their own, they just don't seem to work together.

 

[jungle71]

yup the timings are different from each other.if you can in your bios manually change the timing of the RAM 9-9-9-25 and see if that works, that way each of the four will be forces to use the same timings.

 

[Guy Robinson]

yup the timings are different from each other.if you can in your bios manually change the timing of the RAM 9-9-9-25 and see if that works, that way each of the four will be forces to use the same timings.

changed it to 9-9-9-25 in BIOS and still no luck, any other ideas?

 

[jungle71]

to be honest i have no clue, what else to try. bios update?

 

[Guy Robinson]

to be honest i have no clue, what else to try. bios update?

bios updated.. still no luck

 

[RetiredChief]

In bios have you selected use XMP, Profile 1
As to Timing and Voltage their XMP values are the same for what are displayed.
800MHz, 9,9,9,24,41,2T @ 1.5V
NOTE there are several other paramters that are not displayed in CPU-z and these are normally auto.

Recomment that you use the XMP profile 1, if that does not work try raising the DIMM voltage by .05 (1.550). Test using Prime95 min of 1 hour (most run for several Hours) - NOTE: Monitor cpu temps do NOT let it go above 85C. Then, if that works back off (ie try 1.525V) untill prime 95 indicates memory errors.

Max dimm (RAM) voltage for IB is 1.575V.
.. Some MBs load down when more than 2 Modules are installed, shouldn't but fact of life.
.. Maybe just a small timing diff in one module that raising the Dimm voltage will correct

Added:
Quick question, I looked at your Screen shot and there are diff in Jedec 1,2, &3, but not XMP.
When looking at the Memory tab which only one pair at a time installed is Profile 1 (XMP) selected for Operation. and do both sets display identical values.

2nd added:
.. Still no luck, Switch nationality to Irish - Just kidding - LOLs
.. But try, with one pair at a time runing prime 95 for 1 hr - WITH bios set to use XMP/profile 1

 

[Guy Robinson]

In bios have you selected use XMP, Profile 1
As to Timing and Voltage their XMP values are the same for what are displayed.
800MHz, 9,9,9,24,41,2T @ 1.5V
NOTE there are several other paramters that are not displayed in CPU-z and these are normally auto.

Recomment that you use the XMP profile 1, if that does not work try raising the DIMM voltage by .05 (1.550). Test using Prime95 min of 1 hour (most run for several Hours) - NOTE: Monitor cpu temps do NOT let it go above 85C. Then, if that works back off (ie try 1.525V) untill prime 95 indicates memory errors.

Max dimm (RAM) voltage for IB is 1.575V.
.. Some MBs load down when more than 2 Modules are installed, shouldn't but fact of life.
.. Maybe just a small timing diff in one module that raising the Dimm voltage will correct

Added:
Quick question, I looked at your Screen shot and there are diff in Jedec 1,2, &3, but not XMP.
When looking at the Memory tab which only one pair at a time installed is Profile 1 (XMP) selected for Operation. and do both sets display identical values.

2nd added:
.. Still no luck, Switch nationality to Irish - Just kidding - LOLs
.. But try, with one pair at a time runing prime 95 for 1 hr - WITH bios set to use XMP/profile 1

Tried XMP profile 1: no luck
Tried gradually increasing voltage and still not luck
Is it still worth using Prime95 if it is still only showing 8 GB ?

 

[RetiredChief]

Yes, try just the 8 gigs (2 x 4) first.
1) Check CPU-z mem tab and make sure it is 1) daul channel 2) runing at 800 and 3)timings are correct.
2) then run prime95 for at least an hour.

Then remove and repeat for your 2 x 2 sticks.

You have one of two problems.
A) Faulty stick, or the 2 pairs are not compatable
B) Bad socket - Can check this by first testing the 2 x 8 pair in one set of sockets, then repeat with them in the 2nd pair.

 

[Guy Robinson]

Yes, try just the 8 gigs (2 x 4) first.
1) Check CPU-z mem tab and make sure it is 1) daul channel 2) runing at 800 and 3)timings are correct.
2) then run prime95 for at least an hour.

Then remove and repeat for your 2 x 2 sticks.

You have one of two problems.
A) Faulty stick, or the 2 pairs are not compatable
B) Bad socket - Can check this by first testing the 2 x 8 pair in one set of sockets, then repeat with them in the 2nd pair.

It is dual channel and it is 800 and there it shows the 12 GB.
I tried the 2x4GB in both sets of slots and they worked fine in each so it isnt a problem with that.
So they arent compatible with each other?

 

[RetiredChief]

And both the 2 x 4 and the 2 x 2 when checked OK using prime 95 when tested separately?

 

[toarranre]

Check to see if the RAM is compatible by trying 1X2GB and 1X4GB in seperate channels. If this doesn't work my best bet is that they simply don't like each other.