Can a power outage damage PC hardware?

Question

TL;DR: can a planned "power outage" damage PC hardware aside from HDD/SSD (which won't be connected to the PCs) - mobo, gpu, cpu, psu, dvd, fans?

(the internet says "yes it can" vs "no, only surges are really dangerous")

Longer version: I want to test if my UPS will be enough to power up (don't really know a better term for this) 2 of my PCs. I want to test:

• if I can power up a 2nd PC while the 1st one is already running (or both PCs will just shut down cause "lack of power")
• will the UPS hold both PCs on batteries in case of few second outage (or it will just shut down both PCs cause "lack of power")
• how much time I will have to shut down both PCs in case of a longer power outage (in the end most important test I guess)

I want to test it without SSDs/HDDs as they are the hardware most likely to fail/be damaged/corrupted during a power outage or so I read. I would boot both into a live linux from a USB.

Specs (if needed):

• PC1: 800W PSU, but using PSU-calcs the total wattage of the rig is ~310W (with HDDs, calc suggest a 360W PSU)
• PC2: 850W PSU, while total wattage is ~410W (with HDDs, calc suggest 460W PSU)
• UPS: 1600 VA (so by calcs enough for a 850W PSU - should be enough to keep both PCs on batteries) (yes I probably got scammed few years ago on buying too big PSUs :( but well, I won't invest in a Quad/4th gen i7 builds)

I don't really use the PCs on 100% CPU/GPU and I actually won't have those 2 PCs booted all the time together, but I want to be certain I can do it if I will need both running with both being secured by a UPS :)

So can my tests possibly damage any hardware on my PCs? (total attempts would be like 4-5?)

Thanks!

Answer 1

You are testing so take that into account. There are many (very many in some areas) unceremoniousl power failures that do not damage computers.

Can computers be damaged this way? Infrequent power failures can damage but is very unlikely.

You should be fine testing as you plan.

Answer 2

What happens if the UPS is overloaded, meaning if the protected equipment draws more current than it can provide, depends on the UPS and its quality.

The UPS is being overloaded if the load power demand is greater than the rating of the UPS. In an overload condition continues, some UPS models will automatically shut down, but some may be destroyed, depending on how fast and how big is the overload.

Modern UPS products are designed to cope with overloads. It is commonplace to find overloads of 125% or 150% of rating being allowed by the electronics for some seconds or even minutes. However larger overloads, for example 10 times rating, require faster action by the electronics.

An overload may happen quickly, or slowly increase above the rating of the UPS. Inside the UPS there are current switching devices which can cope with minor overloads for a considerable time until they become too hot. These switches will be damaged almost instantaneously by currents way in excess of their rating.

Answer: The fact that you were sold a too-good PSU might actually play in your favor. From the numbers you gave, the likeliest result is that the PSU will probably support the load, at worst shutting down too early. It's highly unlikely that the connected devices will be damaged in any way. But of course I cannot guarantee anything, so be careful.

Answer 3

This sort of thing can happen anytime anyway (e.g. someone trips overn the power-cable, somewhere else in the house someone causes a circuitbreaker to trip and the PC was on the same circuit).
Worst thing that usually happens is that you loose (unsaved) data. Possibly there is some file-system corruption if the computer happened to be writing to disk on the exact moment when it happened. (Which chkdsk or fsck will usually fix on the next boot. If it isn't repairable I presume you have a proper backup to fall back on.)

It is extremely unlikely actual physical damage occurs when your PC suddenly looses power.
In my 30+ years as IT professional the only cases of hardware damage I have ever seen were not caused by the power-cut itself, but by spikes on the power-grid happening as a side-effect of the power-cut. (Heavy electric motors in a factory which caused induction spikes to run through the power-grid.)
I've seen that 4 times happening. In 3 cases the UPS shutdown or blew a fuse, but the equipment behind the UPS was fine. In 1 case the UPS was fried and the PSU in several computers behind the UPS got fried too. The computers themselves were still OK after the PSU was replaced.

In my home-setup (2 UPS units, one powering a PC and a Synology NAS, the other powering the router and a 2nd Synology NAS) I conduct a UPS test every 6 months just to make sure that everything works as intended. I have never bothered to be carefull with the connected equipment and never had any problems.

As long as you have backups of your important data (and don't do any heavy writing to disk during the test) I wouldn't even bother with removing the harddisks.

Even if a component were to fail I would still consider that a good thing. That component was most likely borderline anyway and going to fail in the near future.