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Asus M2N-Sli Deluxe does not recognize 4x1gb Corsair XMS cl5.0


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Hi there,


been searching this (and ASUS) forum for 2 days now but can't find a sollution for the problem I have. So I hope from some input from anyone here.


short summary: only 1GB of the 4GB memory is recognized on my Asus M2N-Sli Deluxe mobo after mem upgrade.


Let me start from the beginning to give as complete info as possible.


My original config (6 months old):

AMD Athlon 64 X2 5200

Asus M2N-Sli Deluxe

2x Corsair 1GB DDR2 SDRAM PC6400 CL5.0 XMS (productcode: CM2X1024-6400)

Asus 7600GS Silent 256MB

2x Western Digital SATA 320GB 16MB cache

LG DVD writer

LG DVD reader

Aopen Standard 350W PSU

Windows XP SP2

The above config always worked stable (not on Vista btw :sigh!:)


I upgraded some parts now:

AMD Athlon 64 X2 6400+

added identical 2x Corsair 1GB DDR2 SDRAM PC6400 CL5.0 XMS (productcode: CM2X1024-6400), so 4GB in total.

Cooler Master Real Power 520W (i calculated that the original 350watts was quite used at its max so decided to upgrade to this better and higher capacity PSU)


Some days before the new parts arrived i allready upgraded my mobo with it's latest BIOS revision (1302), been working with that revision a few days with my original config, works fine. Default Settings.


2 Days ago i got the parts, installed it and at first boot i got 1 long beep, followed by 2 short beeps and no display, while the harddisks seemed to continue the startup. after some googling found that that code indicates a Graphics card problem. So i took out the Asus 7600 card and inserted it into a somewhat identical other pc here, works like a charm. Some more googling also indicated Memory problems, which was more likely the issue.


In the original config the 2GB was recognized fine as dual channel memory, inserted in slot DIMM A1 & DIMM B1. With the Additional Memory inserted in the remaining slots DIMM A2 & DIMM B2, my thought was that it would automatically see it as 4GB dual channel memory (i've read something about 32bits OS only show up to 3,5GB, but I wish I even got that much:laughing:). But it now see's only the DIMM A2, so only 1GB of the 4GB. I tried exchanging the memory over the ports in all possible ways, all mem modules work fine, but only in slot DIMM A2, slot DIMM A1/DIMM B1/DIMM B2 do not respond at all to any changes. Even if i change back to my original 2GB config (A1&B1) that doesn't work anymore.


So I went ahead and started to configure my bios manually by following some testing parameters on the forum here:

CPU External Frequency: manually set to 200MHZ

DDR SDRAM Clock: 800MHZ (also tried 667MHZ)

DDR2 SDRAM Coltage: tried 1.9V and 2.1V

tCL: 5T

tRDC: 5T

tRP: 5T

tRAS: 12T

1T/2T: 2T


Nothing changes, at Startup it still shows 1GB DDR800 single channel memory, same in BIOS, same in Windows, only 1GB. If I take out the Memory of the A2 slot and leave the other 3 modules inserted, then i'm back at the long beep, 2 short beeps problem.


I also tried this brand new memory from my bro's pc: Corsair 2x1GB DDR2 SDRAM PC6400 CL5.0 Tw.X D. in my pc, but same problems, only recognizes 1GB, only in slot A2.


Also flashed the BIOS to a previous version (1203), no effect. Removed the CMOS battery, resetted the BIOS with the jumper, problem remains.


A PSU issue can't be, it's brand new, all is connected properly and has enough power (520W) I may assume. Is it possible that the A1/B1/B2 slots fail from one day to the other, sounds a bit harsh to me..is there a way to test properly?


What I didn't do yet is run Memtest86 on the memory, but since all modules work fine separately in the A2 slot, it doesn't look like the memory is having problems. Though I can run it if necessary..


So to me it is either an incorrect BIOS config of the memory, or worst case a defective MOBO. This type of memory should work fine with my motherboard, at least that is what I read on the forum here..right?


Of which I thought was an easy straight forward upgrade appears to become a quite frustrating issue and now leaves me with a pc running on 1GB only.


Any help, tips, whatsoever are more then welcome and highly appreciated.:):

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  • Corsair Employee
Please test the new modules by them selves in slots A1 and B1 and see if the same issue occurs, if not then I would test the modules one at a time in slots B2 and A2 to make sure its not a slot problem. And with 4 modules DDR667 would be suggested.
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tried what you suggested but it keeps coming down to the fact that only slot A2 is working, whatever change i make it doesnt recognize what is in slot A1/B2/B1.


I've just send an email to Asus tech support to see what they think about it, i really don't know what else it could be other then a defective mobo?:[pouts:


Though if you have some more tips, let me know, appreciate the response.

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  • 1 month later...

thought i'd inform you guys about the current status.


in the meanwhile i got the motherboard replaced under warranty by Asus, i've now got a brand new one, which does recognize all 4 memory slots.:cool:


I have now inserted 4 sticks of 1GB each, all recognized, but at startup it shows up as 4GB DDR2 800 Single channel..while the mobo/memory supports dual channel? which changes do i have to make in the bios for it to function as dual channel??

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Are the modules all of the same SPD? What model and revision are each module. If they are, then insert two modules in the first and third bank. Do you have Dual Channel? If so, remove those sticks and test with the next two. Do you have Dual Channel? Remove one of each sticks that were paired and put them with the other stick. Repeat the procedure. Dual Channel with each pair?
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what do you mean with SPD?


all i know is that all modules are identical to each other (same brand/type/size/speed/etc). i have allready tried pairing them in the combinations you mentioned, also read the manual (yes i did :eek:) and used the recommended setup for dual config (though it should recognize itself when using 4 slots that it can do dual channel), but all with no result. I have read something here about changing memory settings etc in the bios, would that help? and if so, which settings?

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  • Corsair Employee

Did you try the modules one set at a time and will the system run in Dual channel with only two modules installed?


What DerekT is trying to say is that is sounds like one of the modules may not have the same or correct timings set in the SPD and would be a possible cause of that error. However with 4 modules you should be setting the memory frequency at DDR667 and I would load setup defaults and then set the memory Voltage to 2.0 Volts and set the memory frequency at DDR667 if all of the modules are exactly the same which you can verify they are with CPU-Z.

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resetted my bios, then tried the 2.0 voltage option, together with the ddr667 setting, reboot, but still shows single channel.


when i look in the bios at advanced memory settings, then it shows on auto config that it is recognizes the mem as 5-5-5-18-2, while in my understanding the memory is 5-5-5-15-2. so i have changed it manually to the 5-5-5-15-2 setting but still no result.


screenshots below are from cpu-z in the current situation.








appreciate your help :):

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nooooo, not again, just got this one as replacement of my previous broken board :(:


what is the benefit of dual channel over single channel, is performance much higher or what? if there isn't too much of a difference then i think i will leave it like this, don't want to be 2 months without pc again..:(:

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nooooo, not again, just got this one as replacement of my previous broken board :(:


what is the benefit of dual channel over single channel, is performance much higher or what? if there isn't too much of a difference then i think i will leave it like this, don't want to be 2 months without pc again..:(:


On an Intel Core2 Duo I would advise the RMA. On an AMD system where there is a minimal difference between single and Dual Channel I would advise leaving it as is.





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