RAM has stopped working in dual channel mode

[Steve]

Hi guys,

I rebuilt my PC recently with new hard drives and XP x64/Ubuntu Breezy. I started getting crashes and errors in XP, which after some research looks to be down to memory errors.

I have two sticks of 512MB Corsair XMX3200XL, an ASUS A8N SLI Deluxe and an Athlon 64 Winchester 3200+.

The errors, according to Memtest86+, occur during test 3 in the ~825-835MB region (only a couple of specific bytes, however.) I've tried cutting out overclocking, taking timings to slower than SPD and still no luck.

I then tried to see which stick was dodgy. Turns out on their own, they're fine. I put them back and got errors again (different memory addresses, but exact same symptoms, almost like I'd swapped the bad and good stick around, but maybe I used different RAM slots.)

Finally, I landed the sticks in single channel mode, still the pair of them installed and I get no errors, seemingly (need to run longer testing to be certain, but the errors don't appear when I expect them to.)

Oh, I tried pumping 3.0V through the RAM too, and that didn't help.

So, any ideas? I can't see how it's the RAM, but what do you think? Motherboard? Perhaps the memory controller on the CPU has gone a bit... naff?

Thanks for the help guys.

[kalniel]

Can you verify that you have the problem with both dual channel positions on the motherboard?

[Steve]

The RAM started life in A1 and B1. In later testing I moved to A2 and B2 - still got errors. It might be worth noting that the RAM has to pushed in pretty damn hard to ensure a good contact with the slot, else the system will fail to POST.

[Lee H]

IIRC you can only use 1 of the banked pairs when using 2 sticks of memory for dual channel mode. Knowing Steve, he's got them in the right slots so it could be a memory failure. This is not a common problem but with everything electric - things like this can happen.

Steve - I would recommend RMA'ing them to point of purchase so they can be tested and changed accordingly.

Best Regards,

[Steve]

IIRC you can only use 1 of the banked pairs when using 2 sticks of memory for dual channel mode. Knowing Steve, he's got them in the right slots so it could be a memory failure. This is not a common problem but with everything electric - things like this can happen.

Steve - I would recommend RMA'ing them to point of purchase so they can be tested and changed accordingly.

Best Regards,

I'd love to think it was RAM failure (easiest to fix) but the stuff works fine in single channel mode as the same operating speeds and timings. That hints to me that it's not the RAM

[Steve]

I just checked it wasn't something silly like my PSU. Software was reporting 12V @ 11.25V, so I dived in with a multimeter and got 11.99V - cheers then

[farooqm]

Do you have access to another motherboard or know anyone that won't mind you putting the memory in their board just as a test. This is the easiest way to prove if it's RAM or motherboard.

[Steve]

OK I've done some more testing. Just so that anyone not familiar with the A8N SLI is up to speed, the DIMM arrangement goes A1A2 B1B2 where A/B is the channel and 1/2 is the slot number.

System will not complete POST with:

- One stick in A1 or A2
- Two sticks in A1 and A2

System will POST but fail Memtest86+ with:

- Two sticks in A1 and B1

System will POST but fail to detect a stick of RAM with:

- Two sticks in A2 and B2

System will work properly with:

- One stick in either B1 or B2
- Two sticks in B1 and B2

At the end of all that then. I can think of two possible problems.

1. One of the mem controllers on the CPU is buggered.
2. There's a problem with the A1/A2 DIMMs (or traces) on the motherboard.

I guess I'm gonna have to take my CPU elsewhere to check it out, unless somebody else has experienced the same symptoms before?

[Lee H]

A1 and B1 are to be used for dual channel with only 2 sticks of memory (the manual states this )

If the memorys passing single channel and failing dual channel then it could well be the CPU has an issue with the memory controller.

[Steve]

A1 and B1 are to be used for dual channel with only 2 sticks of memory (the manual states this )

I know that, it's been running like that for the last year.

[herulach]

If you have to push the thing in really hard my money would be on the traces on the board.

[Noni]

Maybe try and RMA the board?

There are alot of issues about this on the offical asus forums, faulty boards are the answer.

Good luck.

[kalniel]

Agree with your diagnosis steve.

Have you moved the computer much? The having to push the RAM in hard suggests to me you've got a faulty contact somewhere - either through dust/dirt or through damage. If you're failing to get a 100% good connection at all places then dual channel could be affected.

Otherwise I'd also agree that the memory controller on the processor sounds at fault. Unusual.

One final thing I don't think you mentioned was whether you have tried clearing the CMOS and/or updating the BIOS. I know that it was all working before, but it's a cheap option to try

[DanceswithUnix]

One final thing I don't think you mentioned was whether you have tried clearing the CMOS and/or updating the BIOS. I know that it was all working before, but it's a cheap option to try

Now that rings a bell with me. My board (not the Deluxe) arrived with an out of date BIOS, and I got memory errors with my Venice CPU.

I found that it worked fine in single channel mode, and from that base updated the BIOS. It now works fine.

Now the fact that your memory seems to have worked in the past makes this seem irrelevant, but stranger things have happened!

[Steve]

I've had A8N SLI's (yes, one died) since a year or so ago - I've always kept the BIOS pretty up to date

Gonna drop the CPU into another machine soon to be sure of the root of the problem.

Thanks for the help guys.

[behappier]

Steve,

I got the exact same problem and quite eager to see how you solved yours!!
Cheers