Thinkpads Forum

Hello, Everyone,

Recently I bought another 1gb RAM manufactured by Lenovo and upgraded my system from 512mb to 1.5gb of memory.
After that I ran into several application crashes and decided to use prime95 to run torture tests on the memory. The test results are always errors within one or two minutes.
The weird thing is: when only one memory module (either 512mb or 1gb) is installed, I got no error even running prime95 for hours! So there should be no problem with the new memory I bought (I guess so).
So I run cpu-z trying to figure out where the problem is and cpu-z shows the memory is running in Dual-channel mode when BOTH memory modules are installed.
I am quite confused since as far as I can remember, I must have a pair of memory modules of the same size and same speed (at least) to run in Dual-channel mode. Then how did I get Dual-channel mode on 1.5gb of RAM? (Please correct me if I am wrong)
I doubt it's this Dual-channel mode that caused the crash. But nowhere in the BIOS setup can I find an option to disable it. I even updated BIOS to v2.03 but the problem still exists.
Does anyone have the same problem here? Or is there a way to disable Dual-channel mode?
Thanks!

kingston 1G and original 512M here, no problem

Well I have the same problem as you, I added 1 G to my original 512, the 1 G is from newegg.com, Transend. Unfortunately my ThinkPad freezes from time to time, for instance when I want to burn a DVD and when I push it too hard. I would say once or twice a week. I ran Memtest but no errors came up. So I just learned to live with the 2 crashes a week... although it would nice to eliminate these, but I do enjoy the extra push I am getting from the 1 G, I may end up removing one of the two sticks.

I'll follow your thread, I am interested in your lead regarding the Dual Channel.

Thanks.

Were you able to disable dual-cahnnel mode? Did that have any effect on the crashes?
Let us know ycd21278.

You do not have to have matching modules in order to use dual channel RAM, this has been true since the Sonoma 915 Intel chipsets which started on the T43.

It sounds like you may just have a bad module, here is what I recommend:

*Download Memtest86 and burn it to a CD, it is bootable
*Start with your RAM in the current configuration which crashes and run Memtest; it will probably fail
*Reverse your modules in the slots and run Memtest again, if it fails continue to next step
*Start with one module in one slot, leave the other one out, and run Memtest; if it fails, we know this module is faulty. You may want to test it in the other slot as well
*Run memtest on the second module, testing in both slots ideally. Again, if memtest fails then this module is defective.

While it is unlikely both modules are defective, it is possible.

You said both modules are original Lenovo RAM?

Let us know!

Sorry for the late reply.
Yes, both of the modules are original rams from Lenovo.
For the first few days, I ran all the tests on all the possible combinations of RAM modules I can think of, and everything seemed fine except when both modules were installed.
But just yesterday I ran memtest86 on this single 1GB module it crashed. After several runs memtest86 either showed errors or just crashed. It really surprises me that for the first few days, no matter how I tested this new module, the tests all passed.
I wish I discovered that sooner. So now I have to tell them this RAM is defective and get a replacement from Lenovo.
Thank you guys for the replies!

Certainly sounds like that 1GB module is defective, but make sure to test the other one as well.

Let us know how it goes!