A simple remedy for a basic intermittent fault in my desktop

[cobaka]

Fixing a simple hardware fault.

Recently my desktop PC 'crashed' - at first intermittently and after that completely. I post this because the remedy was very simple and the reward good. I don't bother to mention common knowledge, such as care with mains power or protecting your system from static discharge. This is not an encyclopedia of PC maintenance.

1. My desktop is an older unit, BIOS date: September 2011.
2. The CPU: Gigabyte Technology Co., Ltd. Z68X-UD3-B3
3. Service history: A good number of years of reliable operation.
4. OS & memory: FossaPup 96-CE running from 8GiB.
5. Failure record: Over some interval of weeks the OS would fail so that the screen would toggle between darkness and a normal background.
The power switch was the only remedy to the problem.
Eventually cycling the power switch would not remedy the problem; I didn't hear 'POST'-test beep when I turned the power on.
The screen remained dark. My set was completely unresponsive.
6. The remedy: I unplugged all rear-panel connectors (incl. mains power chord). I removed all cards (and specifically both memory cards) and ran a clean cotton cloth twice across the bus contacts on every card. After re-assembly the system re-booted normally. Date: 2024-June-6th. Don't over-do the contact cleaning. One or two wipes is sufficient. Edit. Avoid touching the edge connector contacts with fingers - even fingers you imagine are clean.

Later:
Still working, not turned off in the intervening 2 days.
If your set fails with these symptoms - then try this simple remedy.

What's going on here?
My PC system (and yours too) depends on synchronization with a clock running at several GHz. Any contact resistance between the bus and a "finger" on a card (eg a memory card) will ruin this synchronization. Do the maths! A few tens of ohms of resistance, combined with a few pF of on-board capacitance will skew the clock timing signals by a few nano-seconds. That's all it takes to 'kill' your PC. Wiping the edge-connector contacts removed this small resistance. My beloved Puppy woofed again! Oh joy! Oh happiness!
Don't forget to back-up your files regularly. Diligence has it's own reward.

собака

[chilibowl]

very good advice , Co~baka - so-sabka

I used to remove my memory Cards and usea VERy Light Penetrating Oil \<CAIG / Cramolin > on them to clean the Contacts .

I think That i shall try Isopropyl Alcohol on them to clean off any residue , since Alchol is a safe -almost universal solvent.

adios-chilibowl

[cobaka]

@chilibowl

I think That i shall try Isopropyl alcohol on them to clean off any residue

Sounds good to me.
I would avoid oil.
I hope iso-propyl alcohol solves your problem.

cobaka.
In Russian, a fully-grown dog.
Some suggest I should use щенок (a young puppy) - but how many people can deal with the character "щ" or "н" (not a Latin "H", but the character (in Cyrillic script) for "N")? It's very confusing for a young lad!

[greengeek]

I would avoid oil.
I hope iso-propyl alcohol solves your problem.

I'm not sure about this. Alcohol can absorb water from the atmosphere (not sure about isopropyl...)
I remember back to 1979 when I started working on mainframe computers which had many pcb "cards" inserted into wire-wrapped "backplanes" - and every connection was coated in gold - they gave us a little can of special oil that was to be wiped ("sparingly") across every connector that had been wiped clean.
The thinking was that exclusion of air also excluded water and corrosion.
Maybe there are special oils today that have the same effect?

[mikewalsh]

@greengeek :-

Wouldn't such an oil need to have electrically-conductive properties? AFAIK, the thinking behind the use of iso-propyl alcohol - essentially, a sterile, highly-purified alcohol - is that you would wipe the contacts clean first, THEN leave it for a few minutes before re-plugging everything back in again. This gives the alcohol time to evaporate - which it WILL - and because it's highly-purified, it leaves zero "residue" behind.......hence, everything is once again squeaky-clean.

Perhaps something among the following?

https://www.dupont.com/molykote/electrical.html/

Mike.

[greengeek]

Perhaps something among the following?
https://www.dupont.com/molykote/electrical.html/

Interesting link. Yes, I imagine we must have used something like one of those specialty coatings. I have no idea what might be the difference between a "conductive lubricant", and a "dielectric solution" - but that's quite a list of options.