[Gllug] OT: Burnt out power supply

[Peter Ball]

On 20 Jun 2006 at 20:50, Adrian McMenamin wrote:

> A few days ago (when the weather was at its hottest) I noticed my
> computer smelt bad when left off (!), so started unplugging it from
> the mains when the desktop was switch off. Forgot to do that last
> night and woke up to a non-functioning box.
> 
> Took a gamble it was a burnt out power supply and in desperation
> nipped through the empty roads to PC World to buy a new (higher rated)
> one. And, thankfully it worked - making it worth paying the 50%
> premium.
> 
> But why would it burn out when off? Dodgy transformer? Heat just got
> the better of it?

Just some thoughts:

I've just been doing some power consumption tests because a customer was 
complaining about their electricity bill.

Sample system based on 300w power supply, 2.0Ghz Intel Celeron, 512MB ram, 
40GB hd and comparison between 17" crt against 17" tft.

Power supply not connected to anything and just plugged into mains and supposedly 
switched off pulled 12w = 105 kwh per annum doing nothing.

Computer switched off also pulled 12w so practically all that must be going into the 
power supply.

17" crt not connected to anything and just plugged into mains and supposedly 
switched off pulled 12w = 105 kwh per annum doing nothing.

17" tft not connected to anything and just plugged into mains and supposedly 
switched off pulled 7w = 61 kwh per annum doing nothing.

For a PC used for normal working hours about 40% of its power consumption occurs 
when it is "switched off".

For desktop PCs over 1 year old I do a slow but regular replacement of dead power 
supplies - not accurately measured but maybe upto 1 pc in 5 or 10 per annum.  I will 
go out of my way to avoid supplying a case with a non-standard form factor for the 
power supply.

>From what I can remember I have the feeling that cheap servers (running 24x7 and 
not power cycled) using desktop PCs have hardly any power supply failures.

The solution I came up with to make sure that the desktops minimized power usage 
was to set standby to a reasonable setting and plug pc into a surge strip which is run 
to a mains switch with neon on wall at eye level which is then run to the mains socket.  
I've found my users to be supportive.  The key is to make it easy for people to act 
responsibly :-)

Peter Ball




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