Wonder if the number of found CPUs should give me an idea ...?

There are ways to block memory addresses.
In 9x you can reserve a chunk. There are other ways in other os.
The problem is that you need to nail it down to an address, so memtest needs to finish.
Search here. I did a post on it a while back.

In your case... Try disabling the cache and rerun.
If it works, you could try a thorough wash of the cpu and board and hope it's random conductive fluff.
If cleaning doesn't work but cache off does... congratulations on your covington celeron.

If disabling cache and cleaning doesn't work...
There's always underclocking. 66fsb.
If that fails, it's faulty. Probably caps,but could be anything.

Memtest doesn't finish. Freezes up completely at appx 19% progress, first pass. Even the timer stops.

Cache must be worth a try, though - but I've tried 2 different CPUs 🤷‍♂️

Being an Intel motherboard, changing FSB is not an option, unless I play around with masking pins etc. I do have a slotket with a Mendocino, though. Worth trying too ..

Give it a good wash in the sink with a toothbrush.
All of it.

Rinse off with alcohol if you have it. If you don't, the sun does fine in about 4hrs. Flick it as dry as you can first though.

And the Intel BIOS didn't give the option to disable cache. I did however enable ECC of the cache to no avail. Celeron on slotket didn't POST. Cleaning up next ..

Bad capacitors can lead to unstable memory.

Kahenraz wrote on Yesterday, 16:26:

Bad capacitors can lead to unstable memory.

Very valid point. The don't look bulging or anything, albeit I am aware that that's no guarantee ..

Did you set ram to 66?

H3nrik V! wrote on Yesterday, 16:56:

Kahenraz wrote on Yesterday, 16:26:

Bad capacitors can lead to unstable memory.

Very valid point. The don't look bulging or anything, albeit I am aware that that's no guarantee ..

There is no guarantee. I am speaking from experience, though. I had a video card repair with a defective capacitor that I could barely see. Sometimes they can go bad without any bulging at all.

Repair shops hate me. I fixed defective memory on my video card with this one neat trick.

Although you can't test capacitance in-circuit, I have read that you can test ESR without removing them. This could provide some additional information on which one might be failing. But to be honest, boards of this age always benefit from a complete capacitor replacement, since many of them overlap the era of capacitor plague. They are also just very old in general.

myne wrote on Yesterday, 17:12:

Did you set ram to 66?

There's nothing to set. All auto detect 😕

if you have another PSU, try running with that one to see if test completes.

randi wrote on Yesterday, 19:45:

if you have another PSU, try running with that one to see if test completes.

Could try that, yes. Not sure about it, as it runs both my P2B-DS with 4x256 as well as my CUSL2-2 flawless 🤔