Dell XPS 420 - Static Elec. Problem?

datostar

After 6 or 7 years of heavy use, my Dell XPS 420 Desktop has started to intermittently freeze on the BIOS startup screen when the little bar showing startup stops part way across. The cure for this is to unplug the power lead, wait a little while, press the power switch on the computer, often accompanied by a little fan flurry as residual power is used up, then plug the power lead back in. Startup then usually continues uneventfully and the computer runs fine all day. Googling reveals that this is probably a static electricity problem but I'm curious as to why this should only manifest itself after several years of use. Might it indicate a problem with the power supply or motherboard? The onboard audio chip failed recently and I installed a Creative SoundBlaster card to restore sound.

AJXX

Sounds like an issue with either the power supply unit or somewhere a long the lines an earth. If the issue came to light after you installed the sound card is it possible that you've forgotten to re-connect a cable or knocked something out of place?

grumpycrab

A stab in the dark - replace the motherboard battery.

datostar

I'll open it up again and recheck all connections, plus replace the CMOS battery. I suppose if all else fails I could unplug the power cable every night at shutdown. That should let everything discharge.

datostar

Checked all internal connections which seem OK. However, once CMOS battery was out I noticed it was dirty and sticky. After cleaning it was still delivering 3v when I tested it (not bad after 7 years) so I put it back in and no problem on 2 subsequent bootups. Surprisingly, with the battery out for 10 minutes and the power lead disconnected, time/date and BIOS settings were retained. I do keep things clean inside the case but I must confess that I hadn't thought about the cleanliness of the battery.

Strider590

datostar wrote: »

Checked all internal connections which seem OK. However, once CMOS battery was out I noticed it was dirty and sticky. After cleaning it was still delivering 3v when I tested it (not bad after 7 years) so I put it back in and no problem on 2 subsequent bootups. Surprisingly, with the battery out for 10 minutes and the power lead disconnected, time/date and BIOS settings were retained. I do keep things clean inside the case but I must confess that I hadn't thought about the cleanliness of the battery.

Should really be 3.3v, but normally work as low as 2.7v

If its sticky then it's leaking.

I think your problem is the power supply, i'd say it's shutting down a rail +12,-12,+5, or +3.3 due to a perceived fault. The only way to reset this is to disconnect from the mains.

The root cause of this could either be the power supply OR something else in the system, but knowing Dell and taking to account the year of manufacture, i'd not be surprised to find bulging (faulty) 1000uF capacitors somewhere on the mobo or in the PSU.

http://en.wikipedia.org/wiki/Capacitor_plague

Dell use their own motherboards and use cheap components, the bigger mobo brands, like MSI, Asus, Gigabyte, etc, tend to use solid high quality Japanese made capacitors which don't tend to fail.