obscure memory error, any ideas/thoughts?

ragingphoenx · Rated PG Joined: 18 Nov 2006 Posts: 4

First of all, forgive me if I'm intruding on your forums, this just seemed like a good place to get an answer.

Background:
I'm running a Compaq Presario 8000z with an Athlon XP 1800 (it's an old system, I know). About a year and a half ago I decided I needed to upgrade a bit, so, among other things, I bought a gig (2x512) of pc 2100 ddr (PQI MD641GUOE-X2 to be exact). From that time until roughly 3 days ago all has been running well.

Problem:
So 3 days ago I start getting random memory read errors, some of which are causing hard reboots and screwing up system files. I run memtest86 from a knoppix cd to see what it will tell me and I get a bunch of errors during the last few % of test 5. Figuring one of my dimms is bad, I pull one out, rerun memtest and...go figure, no errors. So with the single dimm in I get my OS up and running again. But then curiosity gets the gets the better of me and I dig back out the knoppix CD and rerun the memtest, but this time with the other dimm in (the supposedly bad one).

This is where it gets perplexing, the memtest got no errors. I go back to the full gig configuration and run memtest, and get errors again, still in the last few % of test 5. Now, completely confused I run a memtest on each possible configuration (each dimm in each slot separately, and the two configs with both in). In each case with a single dimm there were no errors, and all tests with both dimms had errors (though the # of errors did vary from 30 or so to around 30000).

Anyone ever heard of anything like this, or maybe know where I might find an answer?

dadx2mj · Posted: Sat, 18 Nov 2006 11:55:01 Post Subject:

First thing that comes to my mind is one of your ram slots on the mobo is bad. Try running memtest with a single stick of ram in the different slots to see if you can pin it down to a bad ram slot.

ragingphoenx · Rated PG Joined: 18 Nov 2006 Posts: 4

Tried that, either stick works in either slot individually, it's only when both are in that I see the errors.

edvallie · Posted: Sat, 18 Nov 2006 12:34:12 Post Subject:

Maybe there's a problem with the dual channel data exchange that's going on. Do you have a third memory slot where you can use both memory sticks and keep them out of dual channel?

Here's what Test 5 Does, If you were curious

Das Capitolin · Posted: Sat, 18 Nov 2006 12:57:28 Post Subject:

ragingphoenx:

I was all set to review a particular Core 2 Duo motherboard from an "EConomy" manufacturer. They sent out this motherboard, and it did exactly what you are describing. One module of RAM in any slot would pass an hour's worth of MemTest's, but two RAM modules would cause failure.

So this company Sent me another motherboard. Wouldn't you know it, this one did the exact same thing. I had over sixteen different DDR2-800 modules to play with, and all of them did the exact same thing: one module anywhere is good, two modules is bad.

I also found this motherboard to be very unstable with USB devices. It wouldn't even get past POST with a G5 plugged in.

Long story short: bad motherboard. In your case, something in the motherboard has likely failed with age, or from a pre-existing weakness/flaw.

ragingphoenx · Rated PG Joined: 18 Nov 2006 Posts: 4

Unfortunately I only have two slots, though I might be able to beg/bribe a friend into letting me test the sticks in their machine, worth a try at the least.

ragingphoenx · Rated PG Joined: 18 Nov 2006 Posts: 4

edvallie · Posted: Sat, 18 Nov 2006 17:46:17 Post Subject:

kimchiman · Rated R Joined: 02 Oct 2007 Posts: 60 Location: New Jersey

I had the same issue with a new matched pair of corsair ram. It would pass single sticks, but then fail test 5 with both sticks. I rma'd them and the new pair worked fine. All I can suggest is blowing the dust out of the old computer. Definately seems like a dual channel issue if it isn't heat related.