Jump to content
Corsair Community

Installed Memory 3.00GB (2.00 GB Usable)


Infam0us

Recommended Posts

Hey Corsair Forums,

 

I am currently having an issue with 3x1GB sticks of Corsair XMS2. Currently my PC is only using 2 of the 3GB's of RAM installed on the PC. On My Computer it says "Installed Memory 3.00GB (2.00 GB Usable)." I've tested all the sticks individually and they all work perfectly.

 

I believe the problem is that 1 of the sticks is slightly newer than the other two, despite them all being XMS2.

 

The timings indicated on the two older sticks show

 

4-4-4-12, 800Mhz, 2.10V

 

Whilst the newer stick shows

 

5-5-5-18, 800Mhz, 1.90V

 

I have no issue when the two identical sticks are on my PC, however the PC fails to boot when the third newer stick is installed. The only way thereafter to get the PC to respond is a full CMOS reset.

 

I suspect because the timings, and voltages on the sticks are different that this is the issue. But I have no idea what to change them to to get them both to work. The two versions are 2.1 and 8.1 if I remember correctly, can anyone help me please? :)

Link to comment
Share on other sites

AMD CPUs use dual-channel memory. You can use 1, 2 or 4 memory modules. You can't use 3 memory modules. You also should never mix kits of memory even with identical versions as they are not guaranteed to work. Two kits of different versions almost never works.

 

Check your mobo manual to see which two slots will give you the best dual-channel memory performance and remove the third memory module as this will just cause system problems.

Link to comment
Share on other sites

AMD CPUs use dual-channel memory. You can use 1, 2 or 4 memory modules. You can't use 3 memory modules. You also should never mix kits of memory even with identical versions as they are not guaranteed to work. Two kits of different versions almost never works.

 

Check your mobo manual to see which two slots will give you the best dual-channel memory performance and remove the third memory module as this will just cause system problems.

 

Hi Trackrat,

 

I should mention that it was working fine before for a few weeks before this issue happened so I can use three modules as I was previously :) I am well aware of the problems mixing RAM which is why I bought identical sticks, albeit a newer version which did previously work up until a few weeks ago. I suspect the memory timings are at fault here but I can't be sure :)

Link to comment
Share on other sites

The same part number does NOT mean the same RAM module. The version number tells you which ICs are used to manufacture the module. See the Corsair DDR2 IC Inquiry link to the left of the page.

 

Mixing of two different kits is never recommended and not guaranteed to function. The fact that the RAM is two different versions and requires different voltages and timings makes it higly unlikely it will ever be reliable, - even if as you say it worked a few weeks ago?

Link to comment
Share on other sites

So your telling me that even though the extra 1Gb stick I bought recently is exactly the same, as the other two which are a year older in every single way its different just because its 1 year newer? So if I want to increase my RAM I have to buy an entirely new set?

 

I tripled checked to make sure the new stick was identical to the sticks currently inside the PC (CM2X1024-6400C4) and it is, its just slightly newer version which is what I was sold. So you basically have to buy 3GB of new RAM if you want to upgrade? You can't just add another 1GB stick even if its the exact same model and type?

Link to comment
Share on other sites

Am currently running with 1GB of my old RAM and 1GB of my new ram together and its working fine, so surely they are compatible?

 

I'd like to add that they are in the 1 and 3 DIMM slots if this would make any difference? I have 4 in total.

Link to comment
Share on other sites

So your telling me that even though the extra 1Gb stick I bought recently is exactly the same, as the other two which are a year older in every single way its different just because its 1 year newer? So if I want to increase my RAM I have to buy an entirely new set?

 

I tripled checked to make sure the new stick was identical to the sticks currently inside the PC (CM2X1024-6400C4) and it is, its just slightly newer version which is what I was sold. So you basically have to buy 3GB of new RAM if you want to upgrade? You can't just add another 1GB stick even if its the exact same model and type?

 

As noted above, you can only use 1, 2 or 4 DIMMs in a dual-channel PC. The RAM part number does not insure identical memory. You posted that the versions are different which means the ICs are different as the DDR INQUIRY LINK to the left of the page shows.

 

Unfortunately there is no means to guarantee that adding RAM to a system will function without errors so yes if you want to be certain the RAM will play nice in your PC, you need to purchase ONE kit of RAM that has been tested and confirmed to function properly on your platform.

 

You may get lucky and find adding memory works for awhile and then strange system issues develop or you may experience issues as soon as you install additional RAM. Unfortunately this is reality and the reason why it's important to purchase ONE tested and matched RAM kit. :(:

 

See the "guide" at the FAQ's link below for more details on adding RAM to a PC.

 

http://forum.corsair.com/v3/showthread.php?t=71085

Link to comment
Share on other sites

A DUAL-Channel mobo CAN NOT RUN THREE DIMM MODULES. It can use 1, 2 or 4 DIMMs. The same memory in the two memory slots that you are using is preferred to prevent issues.

 

The Mobo's running in single at the moment, least it says it does when it boots up? Would this make any difference?

Link to comment
Share on other sites

The system is probably reverting to single channel because it can not run three DIMMS. You would be best to use the two matched DIMMs in the proper slots per your mobo manual and call it a day or upgrade to one tested and approved four module kit for your system.
Link to comment
Share on other sites

I shall point out that this is a very common occurrance when running three sticks of RAM on an AMD platform with a dual-channel memory controller that does not officially support the use of three DIMMs. Sometimes, the system doesn't even POST -- while other times (as in this particular case) all three sticks are detected in the motherboard's BIOS but the third stick is instead being used for hardware caching and is thus inaccessable by any software program. And on this particular system DIMM slots 0 and 1 (or A0 and A1) have priority over DIMM slots 2 and 3 (or B0 and B1) with three DIMMs installed, forcing single-channel-only memory controller operation with the two accessable DIMMs.

 

Recent Intel platforms with dual-channel memory controllers, on the other hand, do officially support the use of three DIMMs; it's just that the system will default to a Flex memory controller mode.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...