If you haven't already you could try one stick of memory at a time.
Or, you could try a different power supply. Be super cautious about whether it uses a standard ATX connector or not as Dell had some proprietary ones. You'll have to look this one up to be sure.
You can't tell if the capacitors are bad visually. Not all of them fail catastrophically. Especially since yours lasted until 2020 at least to POST a few times, perhaps yours slowly leaked or dried out rather than popping/leaking like the ones that failed after only a few years in use. For what it's worth, bad capacitors are common enough on that model that BadCaps.net has a premade kit just for it...

Unfortunately I don't have another power supply to try. I don't think it's the memory, but I can take all but one stick out I suppose just in case.

Yes I know the caps tend to go bad on these, so maybe that is the problem. How hard is it to replace the caps on something like this? My soldering skills are pretty poor, but if the leads are large enough and not in tight spaces I *might* be able to do it.

I have some Mac pizza box motherboards that use surface mount capacitors. What I did was take it to a hackerspace with a good soldering station. A person there good at soldering helped me with the first few and I was able to finish the rest. Unfortunately, COVID complicates this plan even if there's a hackerspace near you.

I got it to POST but when I shut it down and turned it back on the fan went full blast and it's not posting anymore. This is really strange.

Could you try taking out the CPU and cleaning its contacts with IPA ?

When you took the cooler off to replace the thermal paste, you might have caused it to move and not have good contact.

Make sure to clear the CMOS after this as well.

Ok re-seated the processor. The system boots and I can get into the BIOS.

Interestingly there were a few CPU Temperature Out of Range errors in the log.

Applied thermal paste after cleaned the old paste off both heatsink and CPU?

Did you put in memory in the dell computer?

I'm familiar with Dell desk top computers when I was playing with them that was cast off while ago.

Cheers,

I've given up. At this point I think there's something seriously wrong with the MB. I was able to get XP to start installing, but after the first reboot the system lost video and the fan went full blast. Oh well, it was a crap system anyway. 😀

Not junk. GX280 motherboards on ebay is not that expensive. This is how I built Optiplex 780 this way to save on money back then.

I insist on seeing pictures of your memory removed from your computer. Bad quality ram does this too.

Cheers,

These systems were used in a lab environment and were left on 24/7 for around 10+ years, so it wouldn't surprise me if they're ready to die.

The memory is all the same. I have several sticks.

Very good memory modules.

Get a GX280 motherboard then. If you need to change power supply, it is standard ATX design.

Oh, remember this was from bad caps period with yours. Later ones and the ones on ebay motherboards are already replaced back then and if they say working, should be better success rate.

Cheers,

Would a GX260 have the same cap issues? There's at least one I could snag.

Yeah, I have DELL GX270 and 280. these motherboards have capacitors on these motherboards are known to go bad. I cant say that is wrong with your computer but a visual inspection of the mother board looking for busted or bulging capacitors might reveal something. You can usually visually see the bulging capacitors as they are large.

I bought some NEW motherboards from ebay a while back.

If you suspect a bad motherboard then buy a NEW one.
https://www.ebay.com/sch/i.html?_from=R40&_tr … 280+motherboard

Used to have a few 270s and 280s back in the day when they were quite new. Got them for free from a friend who worked as a CAD coordinator, they upgraded their computer park every other year. Those were the SFF models though. Perfect as HTPCs, at the summer house where space is kind of scarce, etc.

My experience is that the 270's caps went bad quite soon, but never had any problems with the 280s. Due to the small form factor and having both parallel and serial ports, I've actually kept a 280, that at least seemingly still is in mint condition. Used it not long ago, worked like a charm. Used that one as HTPC back in the day, it was more or less constantly powered when I was at home.

If disconnection, cleaning, and reseating of everything that it can be done with won't help, I'd also suspect something with the mobo though. The memory modules in the pic looks like original ones shipped with the computer, and they never gave me any problems.

Also, if you didn't already know, there are four diagnostic LEDs at the I/O shield, that might be helpful when troubleshooting.

If you want to try replacing caps, Chipquik or similar Cerrolow based product helps, if you don't have access to a high power soldering station. The desoldering/soldering job itself is simple, the only thing to mind except the usual stuff like ESD protection and hygiene, is basically the cap polarity. The real problem is that thick multilayer PCB might the heat away, so you never reach the needed temperature to melt the solder with a weak iron. Chipquik works by lowering the melting point.

Normally I'd try and do a cap replacement, but this was in an environment where it was on 24/7 for 10+ years so it's probably pretty worn out anyway.