shutting down question

dragonx_08

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Aug 28, 2010
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after i turn my pc off i turn it off at the power switch on the PSU at the back not the mains socket and after i done that i press the power button in for a few seconds is this safe and recommnded or shouldnt i do it in case i damage components inside my PC
 
I don't understand exactly what you're doing. You say, "After the PC is shut down, you cut off the switch on the back of the PSU and then press and hold power button". Why are you holding in the power button? And seeing as their is no power to the machine, I couldn't see where pressing the power button in will hurt it. But why do it? What is the purpose?
 
well eventually the switch on the back of the PSU could ware out but there will be no damage to the PC from doing this. If you are looking to save electricity then you really should unplug the cord from the wall to save the maximum amount.

@dustinhunt78 the reason for pushing the power button is to discharge the capacitors on the motherboard and should be done like this any time you need to touch the board,
 
Turning off the hard-switch is ok though it will cause the CMOS battery to drain from powering the real-time clock which would otherwise be powered by the 5VSB supply.

Trying to re-start the PC once mains power has been disconnected to quickly drain the PSU's input filter caps is completely unnecessary since the 5VSB circuitry would achieve the same result over 10-30 seconds without exposing other components to an unnecessary start-up power spike.
 


Right. But after EVERY shutdown? LOL And I still wouldn't trust that method to open up the PSU (which I know he isn't doing, but anyway). Touching a capacitor can blow your lid slap off! LOL
 

Motherboard capacitors drain within milliseconds of the PSU shutting down. The only place in the PSU that may still hold significant energy after the PSU is disconnected from the wall is the primary-side filter/storage caps - that's where the 5VSB circuitry draws its 10-30 seconds hold-up energy from; not motherboard caps.
 


I have a friend who actually went to college for and does computer repair for a living. He told me VERY different. He claimed that a couple of DAYS after it was unplugged it could still fry you. His warning is NEVER open up the PSU.
 


As was mentioned above, if you ever are going to open the case up, particularly to touch the motherboard, you do want to do that procedure. It could save YOU from being fried and can save your motherboard as well. :)
 
I'm assuming that this question is in regard to whether the power button should be pressed to drain power from the PC after unplugging it from a power source...

Pressing it won't hurt it while.... not pressing it has almost no chance of being an issue. I've never seen any system/network admin, desktop support, techie, etc hold down the power button to "drain the power" that's built up in the system. I mean... it's theoretically possible, but if I told that to my peers, they'd look at me funny or even laugh.

Simple answer: YES. It's safe. Regardless of which option your question was referring to.
 

If the PSU has valid UL or other similar safety certifications on it (many cheap PSUs have fake marks), the main caps have bleeder resistors that will finish draining input caps within minutes of when the voltage drops below whatever the 5VSB circuitry needs to work and those bleeders are usually in the 100k-1M range. If the 5VSB supply shuts down at 100V, the PSU has 330uF mains cap and a 1M bleeder, the mains cap will be down to about 15V after 12 minutes.

As for your friend's advice, people who are not comfortable with messing with line-level voltages should obviously not mess around with it. Those who are either have at least a reasonable idea of what they are doing or are dying to learn.