PSU issue

[#1]

Is it possible for a motherboard to fry a PSU?
Fitted a new PSU into a PC for a friend after the one they'd had originally died, it was more than 4 years old.
Picked up a slightly higher wattage one (350 instead of 300) but less than 3 months later that PSU has now died; is this unlucky or is could there be something up with any of the hardware that might cause a short circuit?
Cheers

[#2]

I think the answer is no - unless there was a short.
However there are couple of possibilities - blocked up air intakes into the case or just poor case ventilation causing the PSU to overheat and also the possibility that one of the voltage rails was overloaded. An older PC could require a lot of the power on the 5v rail whereas a modern power supply should have much more on the 12v rail to suit a modern CPU and graphics card.
You don't say what make the new CPU was but some are really crappy

[#3]

It was a Trust one... took it back to Maplin where it came from who informed me they couldn't give me a straight exchange but have to send it away to be checked under WEEE regulations apparently.
Wait and see what they say I guess..

[#4]

I'd largely agree with OldJim , probably the ventilation is poor - but of course any PSU that is overloaded can fail, so it could be any part of the PC that is drawing more power than it should has put a strain on the PSU.
Have you put many more cards in over the years ?
Check the power required on each voltage rail if you can and make sure PSU can cope.
Maybe put a significantly larger PSU in if it will fit - about 500W ?

[#5]

Thanks for the advice
There are no extra expansion cards, on board video and sound, uses the ethernet connection and has 1 hard disk and 1 cd drive.
Maybe the PC is failing and time for the bin... see what the testers say and if they send me a replacement or not..

[#6]

Quote from: adiewoo

It was a Trust one... took it back to Maplin where it came from who informed me they couldn't give me a straight exchange but have to send it away to be checked under WEEE regulations apparently. Wait and see what they say I guess..

Don't know what it got to do with the WEEE directive (Waste electrical and electronic equipment) as it's to with disposal not to find out what's has failed. As it failed within 6 months you should have been given a refund without question.
Most PSU will have overvoltage and overload protection. Overvoltage use to be done using what is termed as a crowbar circuit to blow a fuse or the use of current limiting circiutry. Overload by a use of SCR. With an overload the PSU should recover if the overload is removed. Could you see any evidence of burnt out components?

[#7]

No sign of burnt out components and when I tried a PSU from another machine it came on ok

[#8]

Maybe your new PSU was just a bad one then - ! !

[#9]

Learning point - don't waste money on "no name" cheap PSUs - bought one for ~ £12 online fairly recently - failed after 3 weeks - went thru all the rigmarole of returning (still haven't got the postage back!!) and they sent me a new one of the same type - this one then failed after 4 weeks!
Wrote it off as a bad job - went to local Novatech and spent a few bob more on a named PSU( Hyper) - computer is now running fine, quiet and cool PSU.

[#10]

I had used trust stuff before and at a 25 quid thought it would be OK, ah well.
Shall start chasing them today, still miffed that insisted that it has to be sent off.

[#11]

Low-rated PSU's - such as 350W are much more stressed than a bigger one.
I've got a 650W in my desktop
No components desperately hi-rated.

[#12]

Maplin delivered a replacement one this morning - 370W - so we'll see how this one goes.