Can DIMM size be misrepresented to the OS?

[Alex_418]

I just purchased 2x4GB DDR2 to upgrade an old system of mine from 2x2GB. As soon as I installed the new RAM I experienced BSODs. On further investigation I found that one of the sticks resulted in many memtest errors (>3000).

Additionally, both POST and memtest detect 2GB of RAM. The stick was sold as 4GB. The strange thing is, CPU-Z sees 4GB too. Is it possible to modify a DIMM so that it reports its capacity incorrectly and tricks CPU-Z? Or is it more likely that the stick is really 4GB but memtest detects 2GB because it has so many errors?

 

[Petrossa]

Both the system and CPU-Z read the DIMM info of the EEPROM, so the info is usually correct.
If you are using an old version of Memtest, it will throw errors out at you as it was designed to only read a max of 2Gb.

 

[Alex_418]

But what about the fact that it also says 2GB detected on the POST screen?

As for memtest, it is memtest86+, from a recent system rescue CD image. Is this likely to be an old version? How can I check?

 

[Petrossa]

Nah, that's the newer version.
Hmmm.
Since you're using DDR2, it's quite likely that your motherboard does not support 4Gb in one slot since a lot of those older boards only supported 2Gb per slot.
Which board is it?

 

[Alex_418]

It's the P5QPLVM-EPU (https://www.asus.com/Motherboards/P5QPLVM_EPU/). I did check before buying and it does indeed say max 8GB RAM. However, I just checked the list of supported memory modules, and none of those listed are 4GB modules. So maybe the 8GB figure on the specs page is wrong.

I wondered about a firmware update but I already have the latest revision of the BIOS. Please do let me know if you have any other ideas.

 

[Alex_418]

Some updates:

1) Both sticks individually fail memtest: one with 18 errors, the other with 5000+
2) Both sticks show up in BIOS, POST, SystemRescueCD and Windows system info as 2GB
3) Only in Speccy/CPU-Z do they show up as 4GB
* I read only somewhere that the figure shown in CPU-Z is not based on the actual memory chips but just on a number reported by the controller
4) On closer inspection of my motherboard manual, the sticks (KVR8002DN6/4G) *are* supported by the motherboard

At this stage, I assume this is most likely to be caused by defective RAM chips.

 

[Petrossa]

It's the P5QPLVM-EPU (https://www.asus.com/Motherboards/P5QPLVM_EPU/). I did check before buying and it does indeed say max 8GB RAM. However, I just checked the list of supported memory modules, and none of those listed are 4GB modules. So maybe the 8GB figure on the specs page is wrong.

I wondered about a firmware update but I already have the latest revision of the BIOS. Please do let me know if you have any other ideas.

It has been my experience that even though the board specs list a max of 8Gb, this is rarely the case. And the fact that the listed supported RAM does not include any 4Gb sticks just highlights the point.

 

[Petrossa]

Some updates:

1) Both sticks individually fail memtest: one with 18 errors, the other with 5000+
2) Both sticks show up in BIOS, POST, SystemRescueCD and Windows system info as 2GB
3) Only in Speccy/CPU-Z do they show up as 4GB
* I read only somewhere that the figure shown in CPU-Z is not based on the actual memory chips but just on a number reported by the controller
4) On closer inspection of my motherboard manual, the sticks (KVR8002DN6/4G) *are* supported by the motherboard

At this stage, I assume this is most likely to be caused by defective RAM chips.

The fact that in POST they only show up as 2Gb further reinforces the idea that the board does not support 4Gb per DIMM slot.

 

[Alex_418]

Ok. As I said, the manual does list these RAM sticks, but only in a single 1x4GB configuration. Oddly, the system won't even recognize 4GB when only one stick is installed.

I guess it's more likely that the motherboard manual is just wrong than that the RAM is defective?

 

[Petrossa]

That seems most likely, yes.

 

[Alex_418]

That seems most likely, yes.

Thanks for your help

 

[Petrossa]

No problem.