Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I am not very good with electricity so I can only guess. So should i be careful with screws and stuff when the pc is on?

share|improve this question
up vote 6 down vote accepted

Personally, if you are "not very good with electricity", I wouldn't risk anything!

Turn the computer off and unplug the power unit.

A screw can do anything from complete a jumper down to short circuiting - and if you forget the screws for a second, there are many components that hold a charge and can hurt if you are not careful.

I remember getting a shock touching a capacitor the first time I opened a computer - not deadly, but enough force to basically lift my hand quickly (can't really explain... just imagine someone lifting your hand quick - against your will!)

So, in answer to your question, not always, but it is sometimes and more importantly, it just isn't worth the risk. Turn the power off before doing any work!

share|improve this answer
Unless if you like to live on the edge. – Tomasi Apr 13 '10 at 1:49
on the edge of low MTBF? – mctylr Apr 13 '10 at 3:07
And if you have a modem unplug the phone line! I got my first shock in a computer from a phone line in a modem – Earlz May 23 '10 at 17:47

Dangerous to the computer, yes. To your own safety, not much, crossing the street is much worst.

The most likely problem is an electrical short, which may divert an over-voltage, or over current to a low-voltage or low-current component, damaging it. Outside of the power supply you are not too likely to see sparks or flames (electrolytic & tantalum capacitors might be the exception to that) from shorts or damage.

I have worked on servers that were designed with hot-plug (i.e. swap in/out while stilling running) power supplies and PCI cards. The PCI card slots were lined with plastic between slots, to prevent shorting neighbouring boards while you inserted or removed a board. These features are not normally found on home or personal systems yet.

In fact I seriously avoid working (hardware wise) on a running system. I've done it, but I've understood it's my fault if I short anything. I've also killed more than one computer by various methods.

share|improve this answer
+1 Dangerous for the computer not the human :) – Johan Apr 13 '10 at 20:15
+1 for interesting videos :) – Earlz May 23 '10 at 22:28

The paint that they apply over the traces is not very conductive, but shorting throughholes, chip leads, and bus connectors could damage your motherboard. Avoid working on or around the motherboard when the machine is powered on, and switch off an ATX power supply completely if possible since they're on even when the computer is off.

share|improve this answer
I will note that I do prefer and recommend to leaving the power supply plugged in (to AC mains) though, as this provides a earth ground for the PC (metal) chassis, which if you used correctly, can reduce your risk of damaging components from static electricity. – mctylr Apr 13 '10 at 3:02
@mct it's important to know though that many computers today will provide quite a lot of electricity to the motherboards even when turned off. For instance, a lot of mobos I have will keep the RAM(it persists dmesgs andsuch) and a few random LEDs lit even when the computer is turned off. – Earlz May 23 '10 at 22:30

You should never work inside of a PC when it is plugged in. The chances of electrocution are fairly low, but if you bump a power connector you could cause an arc that could damage something. Not to mention you could short something.

share|improve this answer
Outside of the PC power supply itself, chances of electrocution are nil as far as I know. Though with some water / dampness I suppose electric burns might be possible, but I cannot imagine a realistic scenario. – mctylr Apr 13 '10 at 3:04

So i just did the same thing, changed my power supply and tried it, it worked when i turned in on, then i went to go put the door back on when i dropped a screw on the powered on motherboard, pick it up at 10secs because i couldnt find it. I no not to work in a powered on computer, i just want to no if i need to get a new motherboard or power supply and what kind of damage i did. when i picked the screw up the computer turned off. Looked like i fried it, didnt make any noice or that kind of sort, just powered off.

share|improve this answer
.... did you try turning it back on ;) – Earlz May 23 '10 at 22:31

Use a magnetic screwdriver that fits the screws well.

Keep the power supply plugged in, but turned off with the switch on the power supply, to keep the case grounded and help prevent damaging components with static discharge.

share|improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .