question regarding memory and Linux (1)
 

Hi,

I have a question regarding memory and Linux:

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I tried the same 512Mb PC133 SDRAM on 2 machines:

a) a Compaq Deskpro - Pentium III 730.8Mhz - Intel i815 chipset; and
b) a Spacewalker PC clone - Pentium III 1.1Ghz - VIA PLE133 chipset.

On the Compaq I had the 512Mb PC133 SDRAM passing all tests impecably, showing no errors (according to Memtest, the one that comes with the SUSE boot cd), but when I tried the same SDRAM on the Spacewalker clone it showed tons of errors.
Nevertheless I had already both WinXP and SUSE10.0 installed on the Spacewalker clone with 256Mb, and now with 768Mb memory they both boot and run fine.

My question(s) here are:
- is it because of the chipset/clock-speed on the Spacewalker clone that the SDRAM showed so many errors, or is it really that the SDRAM is faulty ?
- if the memory is flaky on the Spacewalker clone what operation can I run on SUSE to verify and conclude therefore that it is unreliable ? Maybe perform software compilations ?
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Thnx

There is another option: one of the motherboard memory slots could be bad.

Thanks Jay, there's always that possibility, but I'm sure not in my case.

On the Spacewalker clone I first tried the 512 SDRAM on bank 0 and Memtest showed errors on the 91 Mb area; then I tried the 'good' 256 SDRAM on bank 0 and the 'suspect' 512 Mb SDRAM on bank 1, and Memtest showed erros on the 347 Mb area. Errors point consistently to the 512 SDRAM.

I think maybe the access-rate in the 2 SDRAMs are quite different, although Memtest didn't show any difference -

before) Memory - 256 Mb; rate - 298 Mb/s
after) Memory - 768 Mb; rate - 298 Mb/s.

What I'd like to know is if the errors in memory are going to crop up on the compilation of software on this machine without any obvious warning sign to the user.

Rgds

Bad memory is really treacherous. I bought a brand new pc with two 1GB sticks of RAM last year. It ran without a problem - or so I looked - until I downloaded an iso and verified its md5sum. It was wrong so I downloaded the iso all over. It was wrong again. Same story with the third download. Then I decided to rerun the md5sum: same iso but different result, and a different result afer that and so on. By that time it was obvious that I had a RAM problem. And clearly, that is something that can go unnoticed for a long time; my operating systems seemed to run just fine.

I think the best way of checking the quality of the suspicious stick is to do precisely the same, download any piece of software that has a checksum and verify repeatedly whether the result is correct or not. I imagine you could run a checksum on any of the software packages you already have installed:
rpm -V package name
It will compare the md5sum to what it should really be. If this produces any output at all, it means that something is wrong. Doing so for both computers should reveal whether the RAM is actually faulty or whether it's just incompatible.

I had a stick that would only get goofy after it had been running for a while. 10 minutes with memtest would show nothing. Run it for a couple of hours and all kinds of errors.

Good Luck
Lazlow