16GB or RAM showing only as 12GB

[Raeks]

So I have 4 sticks of 4 GB ram, When I booted it only was showing as 12GB, When I go into Bios it says 12272MN DDR3. When I go into Advanced setting on my BIOS and go to North Bridge conifg, it has them listed as

Dimm0: size=4096 MB, speed 1600MHz
Dimm1: size=2048 MB, speed 1600MHz
Dimm2: size=4096 MB, speed 1600MHz
Dimm3: size=2048 MB, speed 1600MHz

Mobo - Asus M5A97 R2

 

[mrmez]

Have you double checked the labels on the ram?
Maybe somebody zigged when they should have zagged.

 

[Raeks]

Have you double checked the labels on the ram?
Maybe somebody zigged when they should have zagged.

As in ?

 

[Shaun o]

Then your problem may be to do with how the memory chips are populated on the ram sticks them self.

Some ram sticks come populated with the chips on each side of the module.
Where as others only have the ram chips populated on one side of the memory module.

Just have a quick look as it may be the cause as to why the memory is not reading right.
The density, capacity of the ram chips differ in capacity and storage.

Due to the mixing its why you only get 2048 on two of your sticks instead of 4096

 

[Raeks]

So I double checked the sticks, One set is CL 9-9-9-24 and the other is CL 9-9-9-27 , anyway I can change the Cas Latency so all sticks are the same

 

[SBMfromLA]

Perhaps you have 2x4GB & 2x2GB installed, which equals 12GB, which is what your computer is displaying?

What you could do is take out the RAM in slots 0 & 2 (the ones showing 4GB) and placing the RAM from slots 1 & 3 into those slots. If they read as 8GB then the RAM is fine and the problem would be with either your BIOS settings or the RAM Slots themselves. However, if they still read as having 2 GB each, then you either have bad RAM or they were mislabled as 4GB when they only have 2 GB each. I'm assuming each pair were purchased separately, right? You probably had two sticks and got another another two sticks later on.

 

[Tradesman1]

What are the model numbers of the DRAM - should be on the lable of each stick, or look in CPU-Z (free app), can check each stick in the SPD tab and the model should show next to Part number....My gues is also you have 2x4GB and 2x2GB

 

[Shaun o]

Not exactly the best situation in having two sets of memory at different latency and cas timing values.
Rma the new sticks back and match them up if you can with the existing brand and speed, values.

 

[Raeks]

Perhaps you have 2x4GB & 2x2GB installed, which equals 12GB, which is what your computer is displaying?

What you could do is take out the RAM in slots 0 & 2 (the ones showing 4GB) and placing the RAM from slots 1 & 3 into those slots. If they read as 8GB then the RAM is fine and the problem would be with either your BIOS settings or the RAM Slots themselves. However, if they still read as having 2 GB each, then you either have bad RAM or they were mislabled as 4GB when they only have 2 GB each. I'm assuming each pair were purchased separately, right? You probably had two sticks and got another another two sticks later on.

Your assumption is correct, I got another set of 2x4gb, I'll try your suggestion moving them then booting and seeing if they show up as 4gb each. Could the problem be the Cas Latency being different?

 

[Shaun o]

Your going to get the best out of the memory if you have two sets that differ in timing values and cas values.
As I explained if the memory modules on one set of ram sticks are populated on one side of the module.

And on the other set the memory chips populate both sides of the set of memory modules it is why you are only getting 2048MB of memory read instead of the full 4096 on two of the modules.

It is how each memory slot on the motherboard and the memory controller operate.
It cannot function in two modes to read memory in a different chip configuration of single side populated memory and double sided.
The memory controller on the motherboard can only choose one mode to read the banks of memory.

The addressing of memory on a single side populated memory stick, to a dual populated differs.

 

[Raeks]

What are the model numbers of the DRAM - should be on the lable of each stick, or look in CPU-Z (free app), can check each stick in the SPD tab and the model should show next to Part number....My gues is also you have 2x4GB and 2x2GB

Well, Turns out they are 2GB. In CPU-Z the Part number is F3-16000CL9-2GBTD and the Module Size says 2048Mbytes.

Still safe to run them yeah?

 

[Tradesman1]

The Tridents are good sticks, yes, as long as they play nice. If any hiccups, raise the DRAM voltage + 0.05 that may well stabilize them