How do power cycles damage computers?

[lexidobe]

Hello everyone, I am wondering how exactly power cycles (turning on and off) damages a computer over time. Is the damage simply from heat cycles, or is the damage also caused by possible power spikes from starting up? I have also heard that the capacitors on the motherboard, PSU, graphics card, etc wear out a little every power cycle because they go through a charge and discharge cycle. Is there any truth to that either? Thanks

[emosun]

the only thing would be temperatures , and mechanical drives having to spin up

heat is very unlikely as going from room temp to lets say 65c isn't that much of a change to cause long term damage from temperature changes.

the hard drive having lots of startup cycles is slightly an issue as the motors works a bit harder to get the disk up to speed than it does just to maintain speed. even so , it's common to find drives with 3000 startup cycles and still run fine.

other surface components shouldnt be affected by power cycling , capacitors ect.... Capacitors specifically will get old and leak long before power cycles have an effect on them.

if the machine has any mechanical relays (VERY unlikely) like a car , those can wear out from lots of usage but again thats not likely on a computer

[MadmanRB]

This is one of those questions where the only real answer is "it depends"

because power cycling in on itself is not a bad thing but there are factors in a computer that can make it a major pro or a major con.

Its nearly impossible to judge the lifespan of a piece of hardware based on power cycles alone.

I mean that hardware could last years when being powered on and off or it can last 10 seconds.

Rule of averages does not eliminate if a issue will pop up or not, its literally heads or tails and this why this sort of thing is best not thought about and just use your hardware until it dies.

Paranoia about this sort of thing only leads to panic and the number 1 rule in the hitchhikers gude to the Galaxy is:

 

Dont Panic

[Guest]

15 hours ago, lexidobe said:

 I have also heard that the capacitors on the motherboard, PSU, graphics card, etc wear out a little every power cycle because they go through a charge and discharge cycle. Is there any truth to that either? Thanks

It's not the caps themselves that get "damaged" from constant charging and discharging.  It's the components in the path of delivering the charge to those capacitors that can burn up over time.

[lexidobe]

6 hours ago, jonnyGURU said:

It's not the caps themselves that get "damaged" from constant charging and discharging.  It's the components in the path of delivering the charge to those capacitors that can burn up over time.

Thank you. So there is some truth to the myth that power cycles are stressful for computers?

[The Torrent]

6 hours ago, jonnyGURU said:

It's not the caps themselves that get "damaged" from constant charging and discharging.  It's the components in the path of delivering the charge to those capacitors that can burn up over time.

But it is also the caps themselves as well. They can go and often it is the caps.

[Spotty]

3 hours ago, lexidobe said:

Thank you. So there is some truth to the myth that power cycles are stressful for computers?

Yes, there is some truth to that.

For power supplies in particular when the unit has been off (switched off at the wall or at the back of the PSU) the capacitors will discharge. When power is restored the primary hold up capacitor will try to charge, which will cause a spike of high current through the primary side of the PSU - this is known as "Inrush current". As JG said everything in the way of the capacitor can be damaged by that spike of high current. PSUs will often feature 'inrush current protection' in the form of a NTC thermistor to help spread the charge out over a longer period of time and reduce the spike in current.

 

Quote

Inrush Current

Inrush current, or switch-on surge, refers to the maximum, instantaneous input current drawn by an electrical device when it is first turned on. Because of the charging current of the APFC capacitor(s), PSUs produce significant inrush current as soon as they are turned on. A large enough inrush current can cause the tripping of circuit breakers and fuses, and may also damage switches, relays and bridge rectifiers. As a result, the lower the inrush current of a PSU right as it is turned on, the better.

https://www.tomshardware.com/reviews/how-we-test-psu,4042.html#p7

 

Not an issue if you're just turning the PSU off occasionally when you want to change hardware or move the PC to a different room, but if you're turning your PSU off at the wall every time you go to sleep and turning it back on the next morning then the regular discharges and associated spikes when charging can cause additional wear and stress on the unit.

This capacitors will only discharge if you're fully cutting power to the power supply itself by switching the switch at the back of the PSU, switching it off at the wall, or unplugging the cable. If you simply "Shut Down" via windows then the power supply will stay charged and this isn't an issue.

[Guest]

3 hours ago, The Torrent said:

But it is also the caps themselves as well. They can go and often it is the caps.

True.... but very uncommon for a quality unit.

[NineEyeRon]

Don’t worry about it.

 

I powered my PC on and off multiple times a day and it lasted 9 years only had to replace it as the 9 year old AIO leaked (my fault I think too) after a maintenance tear down.

 

It also had a 9 year old SSD in it that that worked as good as new.

[Tronth]

5 hours ago, Spotty said:

Yes, there is some truth to that.

For power supplies in particular when the unit has been off (switched off at the wall or at the back of the PSU) the capacitors will discharge. When power is restored the primary hold up capacitor will try to charge, which will cause a spike of high current through the primary side of the PSU - this is known as "Inrush current". As JG said everything in the way of the capacitor can be damaged by that spike of high current. PSUs will often feature 'inrush current protection' in the form of a NTC thermistor to help spread the charge out over a longer period of time and reduce the spike in current.

 

https://www.tomshardware.com/reviews/how-we-test-psu,4042.html#p7

 

Not an issue if you're just turning the PSU off occasionally when you want to change hardware or move the PC to a different room, but if you're turning your PSU off at the wall every time you go to sleep and turning it back on the next morning then the regular discharges and associated spikes when charging can cause additional wear and stress on the unit.

This capacitors will only discharge if you're fully cutting power to the power supply itself by switching the switch at the back of the PSU, switching it off at the wall, or unplugging the cable. If you simply "Shut Down" via windows then the power supply will stay charged and this isn't an issue.

I was wondering about this, my old rig died because of a tensión spike causing the PSU and the multi socket adaptor to die (my instalation is really crappy), from then on I always cut current during night and when I am not home just in case. I dont know what's worse .