PSU going, or was it just the fuse...

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MB Enthusiast
Sep 22, 2008
South Yorkshire
Hey all,

Today while using the computer (It's been on all day, like every other day), the lights in my home flickered a little. This settled, but then about 30 mins later everything went off (lights sockets etc) and back on - except the PC Pressing the button didn't get it back on, even after waiting a while.

The cable was plugged into a 4 gang extension chord - I have two of these chords, one in a socket of it's own each.

Now not being in the mood for fun and games, I decided to just plug the power lead into the other extension cable, and the PC decided to allow itself to turn on again.

All went well for another few hours, until everything in the house went off again, and the PC refused to boot once more. This time, I tried lots of sockets to no avail. I thought at first the PSU or Motherboard had gone, however I did have a spare PSU lead, so tried that and she now boots up again. (This is while plugged into the second extension lead again).

Was this more likely to be a problem with the fuse in the cable, or the PSU itself? The system is getting on a bit so it wouldn't surprise me if it was the PSU, and it's been a while since I cleaned out the tower - but it seems odd that a new cable lets me work fine, and that the other cable worked after failing once.

There's the slightest of chances that the original cable I was using was an old monitor one, and not a PSU cable originally... would that make a difference?

I think it'll be time to give her her six monthly clean up inside!

Thanks in advance if anyone can help :D
Oh, and is there a software based solution that could tell me if my hardware is drawing enough power from the PSU at all?
Well, if I've ever had a power cut before (split second ones), as soon as the power has come back on the PC will boot without having to wait, but it's possible.
You may be changing things around to quickly to establish exactly what is not working properly (apologies if that is not the case) It is likely that the PSU has some protection against surges and voltage drops. Disconnecting it completley from the mains for a few minutes will allow it to re-sync itself to a good starting point. Yu may simply have been swapping leads during this process. You may also have a dodgy lead.

Always remember. Your PC will only ever fail when you need it most. It is designed to lose all you family photos and almost completed novel at the point that you have no back-up and no hope of mending your now lost marriage.
I doubt the cable makes any difference, and I think the PSU is fine. Modern PSUs (even my 1998 one in my desktop) have some protection against surges etc. and I've had this behaviour quite a bit. Sometimes the computer is still on even though it's not, if you hold the power button down for, say, 10 seconds you should hear a click as the hard drive spins down (you may hear nothing though). Press the button as normal to turn it back on and it should be fine.

At least that's what happens with the desktops I've used.
Well it's been fine so far today, but I'll keep watching it. If it drops again, I'll wait and then try and power it up without touching the cables :)
Just my home I think - the clocks didn't even reset, so the time scale of the cut must have been miniscule.
I'd say it was a surge and not a cut

Now, if you have these frequently it could (read could not will) be worth investing in an Uninterruptable Power Supply. It's basically a battery through which the computer is connected to the mains, when the mains supply is down or when there is a surge the UPC kicks in to keep the computer under normal power until the mains is fine again. They are expensive and not too small.
I'm thinking about getting one of these in the future, mainly because I develop code for a living, and it doesn't matter how often you save, it still is hell when the PC drops! I'll be waiting though as I really should get to replacing this machine anyway as it's getting on a bit now, so will get a UPS when I build the next machine.
Well that suggests a 318w draw (at 100% load), and mines 570w, so I guess I'm ok on that front!

It's a good little tool that, thanks :)
I just factored in ageing and it jumped to 399w suggested. I didn't realise power consumption would go so high with age! Still in the safe zone, but it's something to think about when building the next system as I don't like to replace things often.
I'd question whether consumption really does go up as parts age, I really would. But I'm currently maxing out my 200W PSU in my 'server' (the old computer I use to host websites) and all is still fine
Full load (that computer was not built for Windows Server 2008, and it gets up to 100 visitors at once which is a lot for a domestic desktop connected via a domestic router!)

It has a tape drive, 2 hard drives and a very energy inefficient hard drive from '98. It also has additional cooling, a floppy drive I sometimes use and 2 cd drives the files of which are shared via FTP (hundreds of scans of press releases etc. from a family business)
I'm thinking about getting one of these in the future, mainly because I develop code for a living, and it doesn't matter how often you save, it still is hell when the PC drops! I'll be waiting though as I really should get to replacing this machine anyway as it's getting on a bit now, so will get a UPS when I build the next machine.

What's your definition of "getting on a bit"?
Some parts are getting on for about 5 years old lol

Still works pretty well and runs windows 7 a treat. Not great for gaming though!

Just stripped and cleaned it out (stripped the PSU for the first time - thats about 3 years old, was packed with thick dust). It's all running super quiet compared to normal now, until in a few months time when it's all caked again :D

Did a bit of fresh cable management too, so should help a tad.
Cable management - that's something too daunting for me to consider (inside of the server is like behind a Land Rover Defender's instrument panel - not ap retty sight!) My desktop is almost as bad. Both run fine.

Server is from 2003, Desktop from 2001! Server monitor from 1995, Desktop monitor from 1996 now (one's an unbranded 9" colour CRT, the other's a DEC 14" colour)

Desktop speakers 1996 Cambridge Audio ones.

I also have a Commodore Amiga A500 and a BBC Micro with original dust cover, BOXED Cumana floppy drive and BOXED Microvitec CUB monitor (both with manuals!)

I often have both printers, my desktop and the 2 vintage ones on at once (along with their respective screens)... and I wonder why my lights sometimes flicker!

I do, at least, dust everything out. My IBM Thinkpad Laptop (T60) needed a dust out every week, but still got up to 120C where it turned itself off. Currently awaiting a new processor and fan!!!

Printers from 1992 (first batch LaserJet 4!) and 2001 (LaserJet 4550N with extra tray).

And your 2006 PC is getting on a bit?!

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