Bad DIMM? Or bad motherboard?

[Gandalf90125]

I'm having trouble putting a system together and want some advice from you techies out there.

DIMM A (256MB) has problems on Motherboard 1, regardless of which slot it is located. Sometimes upon boot, the full 256MB is reported as being present; at other times, a lesser amount (like 115MB) is reported. DIMM A on Motherboard 1 will also not complete an installation of Windows98SE without crashing.

DIMM A on Motherboard 2, however, consistently gets reported as being the full 256MB, regardless of slot. Although I did not try doing a Win98SE installation on Motherboard 2, I have run DIMM A in Motherboard 2 for over 16 hours with Memtest-86 with no errors reported.

DIMM B (512MB) on Motherboard 1 behaves normally. 512MB is consistently reported, regardless of which slot the module is placed, and the Win98SE installation occurs without error.

DIMM B on Motherboard 2 has no problems. DIMM B has been used on Motherboard 2 for over six months and was pulled to try on Motherboard 1 for troubleshooting purposes.

So...is DIMM A bad? Is Motherboard 1 bad? Are both bad?

For the curious:
DIMM A - Mushkin PC2100 High Perf 256MB
DIMM B - Mushkin PC2100 High Perf 512MB
Motherboard 1 - AOpen AK77-8XN (KT400)
Motherboard 2 - AOpen AK77 Plus(A)-133 (KT266A)

 

[DAPUNISHER]

The only thing that I can surmise based on your testing is that stick A is either faulty or it's having some sort of problem with board 1's memory controller, being faulty would be damned stranged based on memtes86 results on board 2 and a compatability issue seems unlikely as well since the 2 sticks are the same brand/speed rating/series with only memory size different. Are the timings by SPD? Did you try manually configuring the timings in the bios and if that board supports vDIMM adjusting, upping it a bit? Trying fail-safe settings couldn't hurt either but my personal brand of logic states if it's stable in one board and not the other the surest solution is use it in the board that it evidently works with

 

[Gandalf90125]

Timings are not by SPD. For the two Mushkin DIMMs, timings were set to 2-2-2 and 2T CMD as Mushkin advertises that the DIMMS support these settings. The 512MB DIMM passes; the 256MB DIMM in question doesn't although it does pass at 2.5-3-3. I've tried voltages from 2.5 to 2.65 for the 256MB DIMM but to no avail. These were at fail-safe settings in BIOS.

To throw another variable into the mix, I've tried testing with a Crucial/Micron PC2100 256MB DIMM rated at 2.5-3-3. It works with the questionable AOpen motherboard and also a Shuttle KM266 board at 2.5-3-3 but fails on both boards at 2-2-2. So I still don't know if that one Mushkin DIMM is flaky or if it's that one AOpen board or if it's both.

:-/

 

[DAPUNISHER]

There's no problem with the board, your reply makes it crystal clear that it's time to RMA the 256mb stick because it's flakey, if it runs with relaxed timings just fine then it's not living up to the advertised specs is all, Mushkin will will honor the warranty. The Crucial runs at it's rated speed so no issues there, remember no warranties/garantees are made for running hardware out of spec.

 

[Gandalf90125]

That was my first thought, also, that the DIMM was bad. However, I have been able to run it at 2-2-2 under Memtest on a Shuttle KM266 board and an AOpen KT266A board for over 12 hours each with no errors.

This DIMM is only bad in the one AOpen KT400 board. And the AOpen KT400 board gives me errors with only this one DIMM. I still can't isolate either the board or the DIMM. :-(