RAM-testing - odd errors

[Iznougoud]

Recently, I've experienced infrequent crashes on my A2000. Black of frozen screen, blinking power-LED or just a spontaneous reboot.

This has caused me to check the memory, and the results were so odd, that I had to use my unexpanded A1200 as a reference. This is what I got:

A2000: 1Mb ChipRAM, 128Mb FastRAM. Blizzard 2040. ROM3.1 AOS3.9.
A1200: 2Mb ChipRAM. 68020/14. ROM 3.0 AOS3.1.

MemTest A2000: No errors when Workbench is loaded. Errors reported when Workbench isn't loaded(ChipRAM & FastRAM, which is strange, since I have the same amount of ChipRAM available regardless of whether Workbench is loaded or not).
MemTest A1200: Reports errors.

CheckMem A2000: No errors.
CheckMem A1200: No errors.

Memory Diagnostics (MD) A2000: Now it's getting exciting. Reports errors when Workbench has been loaded. Reports errors outside Workbench when a soft reset has been done. Reports NO errors outside Workbench when a cold reset has been performed(!).
Memory Diagnostics (MD) A1200: No errors.

Now, I find these results inconclusive. To put it mildly. One would imagine that the OS3.9 ROM-image might mess things up, but given the variety of results that doesn't seem likely either.

Does anyone have a clue?

[Iznougoud]

That would be a reasonable assumption. But given the results from testing this far,  I doubt it's a driver issue. On the contrary. A driver issue should cause the errors to occur when Workbench is loaded, rather than the other way around.

@Hodginson; that link proved dead. But from what I managed to find out about it, you're referring to a piece of hardware that would be nice to have, but probably harder to come by than a completely new A2000-setup  :-D

[Iznougoud]

That link worked. I'll have a look at it, although my wiring- and soldering skills arent' what I'd like them to be.

Anyway. Given the contradictions in my testing results. I've decided to focus on MemTest. And as far as I can tell, it reports errors in every environment BUT WB3.9 (I've tested no WB and WB3.1 - it's a reasonable assumption that I would get the same results in WB2.01 and WB1.3 as well). Does anyone even have a theory of what this could be, or could it be that there's a bug in MemTest?

[Iznougoud]

Yes. I noticed. For some reason, it does seem to test FastRAM only though (finds the ChipRAM, but never get passed testing FastRAM). Ah well. I suppose I'll just have to disable the A2040-board and run the test again. Not that big a deal.

This far, it's run 22 passes on the FastRAM with no errors. So that's a good sign. I hope. Doesn't, however, solve the mystery of the random crashes.

Edit: My bad. From the looks of it AAA does check bot Fast- and ChipRAM. It just doesn't allow you to choose either.

[Iznougoud]

Or even more simple, I might switch power-supply. The chance of two power supplies going bad at the same time would be - if not astronomical so at least slim. Maybe I even should consider rebuilding an ATX-PSU..

I am however a bit confused by the output given by MemTest..

[Iznougoud]

Yes. That much I understand. What bothers me, is that the symptoms doesn't vary - MemTest reports errors outside AOS3.9, but can't find any inside AOS3.9. Always. Not sometimes. Other RAM-testers doesn't find any errors at all. Regardless. If this was to originate from the PSU, I would expect the errors to occur on a more random basis. Regardless of RAM-tester used.