Memory error only in dual-channnel seating

[eklass]

i'll keep this short so the diagnosis can begin

Mobo: Asus M2A-VM
RAM: G-Skill F2-6400CL5D-2GBNQ

When I run Windows Memory Diagnostic (or Memtest86), the screen goes all garbled shortly into the test when my RAM is seated in a Dual-channel method. Each DIMM tests good alone, and both test good when seated in single-channel. Below are some test results

Dual channel is paired as 0/1 and 2/3
O = DIMM, X = Empty
+ = pass, - = fail

0123
OOXX -
OXXX + (DIMM1)
OXXX + (DIMM2)
OXOX +
XXOO -


Thoughts, ideas?

 

[Fullmetal Chocobo]

I had an issue with my Asus P5N32-E SLI Plus mobo. I could run a single stick of RAM in it, but when I put two in, it would just beep (solid constant beep). After troubleshooting for a while and several phone calls, the mobo was found to have a bad memory controller. The motherboard was returned and the new one didn't have a problem in the least.

May or may not be the same. Is this a new motherboard you are working on, or did it all of a sudden have problems?

 

[eklass]

Originally posted by: Fullmetal Chocobo
Is this a new motherboard you are working on, or did it all of a sudden have problems?

Newish... I've had it for several weeks already, but I've been troubleshooting the random reboots. Partially to be attributed to horrible ATI drivers. Once that was isolated, I troubleshooted other components until I arrived at this.

 

[eklass]

fishing for more...

 

[Quiksilver]

Have you tried alternating the sticks with just one stick?

Like put in stick "A" and run memtest. If all is good, exchange stick "A" with stick "B" and run memtest again. If that is good too then I could only assume a fault memory controller.

If one of the sticks are bad RMA it.

 

[RebateMonger]

This is a known issue that's sometimes seen. Two memory sticks will work OK when each is run separately, but when you go into Dual Channel mode, they start failing. Apparently the timing in Dual Channel mode is a bit more agressive than in single channel, or it's somehow "harder" on the memory modules.

When I had this problem, I never was able to identify which module was really "bad". The combination of them both together was causing Memtest failures.

There's no fix except to get memory that passes the test. It's NOT a big deal to get memory to pass Memtest86+ in Dual Channel mode. But yours isn't passing.

 

[eklass]

Originally posted by: QuiksilverX1
Have you tried alternating the sticks with just one stick?

Like put in stick "A" and run memtest. If all is good, exchange stick "A" with stick "B" and run memtest again. If that is good too then I could only assume a fault memory controller.

If one of the sticks are bad RMA it.

Yup, see test 2 and 3 in my initial post.

Originally posted by: QuiksilverX1
There's no fix except to get memory that passes the test. It's NOT a big deal to get memory to pass Memtest86+ in Dual Channel mode. But yours isn't passing.

I guess I'm going to have to live with single channel for now. This machine will become a general app/file server later this year, so it's not really worth fixing. Was hoping to nail this down to mobo or RAM, but without a replacement for either to test, I might be OOL.

 

[Nathelion]

maybe you can relax the timings and/or lower the fsb frequency?