If you have NiCd or NiMH batteries for the clock, make sure you don't deep-discharge it. It is my impression that deep-discharging the 3-cell stacks causes one cell to get reversed and this highly increases the risk of leakage. Those cells are typically on a C/10 to C/20 trickle charge, so it needs up to 24 hours to fully charge these cells when they are fully depleted. While I have no idea how long they would last until depletion, I would definitely recommend something like 8 hours of operation in 6 months at least to keep the battery charged.
The cell type used for memory backup is hardened against over-charge at the low trickle rate quite well (because that's the use case the cells are optimized for!), but they don't seem to do well on (repeated) deep discharge, though.

I have seen a lot of different ideas about this, but I have seen examples that contradict all sides.

Not using a computer can kill or protect it:

Hard Drives can die from sitting unused, and can die from use.
The motherboard can die from use, or if it has bad capacitors the motherboard can die just sitting there not even being used.
The batteries inside of a computer can leak and damage or kill the computer if you use it or not
The Computer can become damaged from condensation when in storage, I have a bunch of rusted and corroded computer parts.

I have started to "adopt" a different strategy for this kind of stuff:

Keep the computers in a dry place, remove all batteries when not in use, have extra parts if you can, document everything, have a backup of all the drivers and software, don't use mechanical hard drives, replace bad capacitors before they cause problems, buy more than one computer if you can, only use one computer at a time, only have it powered on when you need it, use a "good" UPS and "good" power filter.

Apart from batteries and mechanical parts, there's not much difference between using and storing. Electronic parts wil age and eventually fail in any case.

I check most of my stored systems once a year. Between that, they are all like Schrödinger's cat: you don't know if they are still working or if they are broken. And by testing them, you actually define their working state. 😉

I keep my retro gear switched off at the power strip when I'm not using it so 25 year old hardware doesn't burn down my house.

Nothing lasts forever, everything has a lifespan. Everything will bite the dust inevitably. That's why emulation and preservation is important I bet in several decades or centuries, emulation will evolve to be as good as the real thing. and there are also the FPGA devices like the MISTer and the SOCs (System on a Chip), which can replicate the old hardware.

Oetker wrote on 2020-06-10, 07:14:

I keep my retro gear switched off at the power strip when I'm not using it so 25 year old hardware doesn't burn down my house.

I never leave anything old plugged in while not using it. But not because I fear it burning down my house. The chance that your smartphone charger does that is actually quite a bit higher.

Well most XT/AT computers and their respective monitors won't do anything when switched off if connected since they're physically cut from AC by their power button.

I imagine fans of all sorts will seize up if not used for years. Of course used ones need oiling every few years as well but at least they keep going

Deksor wrote on 2020-06-10, 09:42:

Well most XT/AT computers and their respective monitors won't do anything when switched off if connected since they're physically cut from AC by their power button.

Not true. AC filter caps (X, Y) are connected to mains even when the power switch is off. And these are what fails first in most old computers.

Also, using a switchable power strip is not a solution either. Unless you buy a premium one, it will only switch one wire. In countries with unkeyed plugs (like in Germany), it may or may not switch the live wire. There's no way to tell.

Unplugging is not only safer, it's also the only reliable way to prevent things like lightning damage. And that's why I'm doing it mainly.

Tbh, it's a bit like car engines: it's not the mileage that causes the most wear (within limits), it's the stopping and starting and running cold.

I know of consumer-grade systems (think: P2 Compaq Deskpro EN SFF) that have been running for 20 years 24/7 with no issues whatsoever in our company's server rooms. Partly that's due to good build quality, partly due to temperature-controlled stable environment, partly due to luck, but mainly because they don't get stressed by booting on and off.

As for whether it's good to boot systems every year or so to check, I don't think that in itself will cause significant wear&tear. It might marginally be good for mechnical parts of the systems (stopping parts from seizing up), but I'd say the biggest benefit is to spot issues as soon as possible and not discover completely leaked batteries etc 10 years after the damage started - but that can be done with a visual inspection too, without actually powering stuff up. Still, knowing things work is good, being able to take action if they don't is good too, so if you can muster the effort, I'd say booting very periodically is a good idea.

Well you learn something everyday x)

Though I don't remember seeing any of my AT PSUs (even cheap ones) with a power switch that would only switch one wire. Now that doesn't mean it doesn't exist !

dionb wrote on 2020-06-10, 10:18:

Tbh, it's a bit like car engines: it's not the mileage that causes the most wear (within limits), it's the stopping and starting and running cold.

that's why the same is somewhat true for hard-drives... those are mechanical machines, and long downtimes can cause mechanical issues, rust etc.

electronics don't have the same issues, sure some components age over time (electrolytic capacitors especially) but I don't think any IC will suffer by not being used.

It's just down to luck.
Take a HDD for example. don't use it and it may seize, use it and your adding to general wear and tear . You can't win either way!

I'd say where your hardware lives (either setup or in storage) makes the most difference. dry, no static or extreme temperatures.
Not stressing old hardware when in use would be the next thing.

Deksor wrote on 2020-06-10, 13:29:

Well you learn something everyday x)

Though I don't remember seeing any of my AT PSUs (even cheap ones) with a power switch that would only switch one wire. Now that doesn't mean it doesn't exist !

Yeah, that has also been my experience. All my AT PSUs switch both wires and the fuse, thermistor and X/Y caps (as well as the monitor output) are AFTER the switch, so the only connection to the mains plug when the switch is off is the ground.

But maybe older or proprietary units are different.

My experience is that untested "attic finds" always have less problems than regular runners.
Also computer museums tend to preserve their hardware in shelves indefinitely.

The golden rules are:
1. Remove batteries. They leak and corrode PCBs. Preferably mod your hardware to accept removable batteries to be stored seperately.
2. Keep dust away.
3. Control moisture. Feel free to use those food-grade absorbing packs.
4. Keep light away.
5. Preferably use anti-static bags (though I don't).
6. All electrolytic capacitors are designed to die in 2015-2025. (80s capacitors live approx 30 years, caps made in 00s died as soon as they left the factory). If you do love your hardware - be sure to replace electrolytic caps with low-ESR long-life ones. That should give you another 30 years of running. Though it may make audio sound a bit more harsh.

That should cover it all. I think that not running hardware is better for preservation. Though computers relying on cassette tape drive shall fail due to deterioration of rubber parts in the drives.

What I gathered scouring badcaps.net for an hour is that in general it's good to energize electrolytic capacitors every couple of years to prevent situations wherein they will need to be reformed. This seems very much in line with the notion of testing equipment at least annually to ascertain the state of one's collection.

interesting, guess I'll have to worry about caps even more ^^

I fire any stored systems up at least every two years to see what working or not. Only ever had one psu go pop in over 20 years and that includes Dell P4 systems and monitors. Or Acer or HP for that matter. Nor the two NEC/Packard Bells I got a few weeks ago. They are stored in a dry double garage. I don't use any desiccant all. Absolutely no need to were I live. Just store in banana boxes and plastic storage tubs with the tops not completely sealed.

Folks that moan about every system/components from late 90s/early 2000s having bad caps do get boring repeating it more than once in a thread.