CMX512-2700LLPT TWINX has one bad module

[gust334]

I have a "matched set" of CMX512-2700LLPT sticks, one of which is causing me grief on an ASUS A7N8X-E Deluxe. I also borrowed two sticks of another vendor's DDR400 from a nearby machine, and those work perfectly in this mobo.

 

Mobo: ASUS A7N8X-E Deluxe

FSB: 133MHz

Memory Mult: 125%

Resulting Memory Frequency: 166MHz

Memory Timings: User Settings

Active Precharge: 5

RAS to CAS Delay: 3

RAS Precharge: 2

CAS Latency: 2T

DDR Voltage: 2.6V

 

I'm using user settings because the SPD gives me 2-2-2-5, but the Corsair online PDF datasheet for this product says 2-3-2-5. I'm using 2.6V because the BIOS warns me that any other setting may damage the memory.

 

I am using memtest86 v1.1 from a bootable gentoo Linux CD for diagnosis; when I have both sticks installed, dual channel works, and I see multiple failures 00000002 throughout the 900MB region within 10 minutes (first pass, test 5). I dialed back the speed from 166MHz to 160MHz and the problem still occurs, although it can take up several passes of memtest86 before the problem is visible at this slower speed.

 

When I install only the problem stick, I see still see multiple failures 00000002 but at lower addresses. Again, the failures happen very quickly at the rated speed of 166MHz and occur more intermittently at 160MHz. I tried the slower 160MHz with derated settings of 2.5-3-3-6 and I still get 00000002 failures reported after several days. :(:

 

When I install only the good stick, memtest86 passes all tests. Then I overclocked the memory clock speed to 173MHz (memtest86 says "DDR345") and the good stick continues to pass memtest86 for several days at 2-3-2-5 2.6V even at this faster speed. :biggrin:

 

I've run out of creative things to try. It looks like one stick of this matched pair is working as advertised, and the bad one cannot function even at a significantly derated speed. My questions are: :confused:

 

(1) What other diagnosis do I need to do before I can get an RMA, and

(2) I purchased these as a matched set; do they get replaced as a matched set?

 

Thanks

[RAM GUY]

Please install the modules in slots 2-3 and set the Dim Voltage to 2.7 Volts and then test the suspect module with http://www.memtest.org. If you still get errors then lets get your modules replaced.

Please follow the link in my signature “I think I have a bad part!” and we will be happy to replace them or it!

[gust334]

Please install the modules in slots 2-3

The ASUS A7N8X-E Deluxe doesn't have slots 2-3. Counting from the processor outward, there is a black A2, a blue A1, then a small gap, then a blue B1. The ASUS manual indicates dual-channel is supported when using B1 and either or both of A1/A2. The only unsupported dual-channel configuration is A1+A2 with B1 empty.

 

For dual-channel, I have been using both blue slots (B1+A1). For single-channel testing, I have already tried all three slots individually.

 

and set the Dim Voltage to 2.7 Volts and then test the suspect module

OK, I have not yet tried boosting the voltage up to 2.7V because of the BIOS warning about damaging the hardware. Questions:

 

(1) Is this higher voltage (2.7V) only for testing purposes, or suitable for continuous use?

(2) What is the highest DDR voltage that Corsair supports on CMX512-2700LL TWINX for continuous use without voiding the warranty?

(3) Shouldn't the modules work correctly at rated speed with the stock 2.6V?

 

I will retest the suspect module at datasheet speeds in all three slots at 2.7V when I get home tonight. Please note that the good module of the pair is working beyond spec at a mere 2.6V when I've tried it in both A2 and A1.

 

Thanks

[RAM GUY]

Well the MB has 3 slots and counting from the first slot next to the CPU, you would use slots 2-3.

 

You are running aggressive modules and sometime the memory controller needs bit more power. All of our DDR1 modules are rated up to 2.9 Volts so as long as you don’t go over 2.9 Volts you should be fine. And since the memory controller get its power from the same source adding a bit more voltage to the memory will help the controller as well.

But if you still get errors with the Voltage at 2.7 Volts then lets get your modules replaced.

Please follow the link in my signature “I think I have a bad part!” and we will be happy to replace them or it!

[gust334]

... But if you still get errors with the Voltage at 2.7 Volts then lets get your modules replaced.

Thanks for the very helpful info on correct operating voltages! :D:

 

I tried 2.6V, 2.7V and 2.8V, and the suspect module solo in all three slots, for a total of nine separate tests all at rated speed. memtest86+ very quickly reported the same bit position failing for all nine tests (although the address varied somewhat). Well, at least it is consistent and repeatable. If it matters, that bit position is consistently reading zero when it should be one.

 

OK, I went to the online RMA request, and after entering all my info and clicking the button, a blank email message popped up and the brower went back to Corsair's home page. So, I manually reentered all the requested information into the blank email message and sent it off... hope that's OK?

[RAM GUY]

Sure that's fine. Please let me know how you make out when you get the new modules!