Failed to boot

[Rocket]

It'll be difficult to find, good luck.


I had a pc (PC1) that worked for years and one day it would not get to post. I took out the PSU and put it in another machine (PC2) I knew worked, and it was fine. I then put the PSU that was originally in the PC2 and put it in PC1 - that worked also. So I put all the parts back to where I started and PC1 refused to start. I repeated this several times with the same result. In the end I just left the PSUs in the machines they preffered and tried not to think about it.

BTW both machines had 2 HDDs and were pretty similar.

[Anthony & Maricel]

Originally Posted by HarryM1BYT

It failed to POST or boot again this morning

After a bit of messing about with the HDD's again, it eventually gave the POST beep then on the next attempt it booted and I'm typing this on it. It now seems like a cold start issue and I've checked the plenums

Seriously, it looks like a PSU problem after all. At least that part looks like a standard ATX unit.

There are 2 types of ATX psu there is a 20 pin and 24 pin make sure you buy the correct ATX psu a 20 pin can be used in a 24 pin socket but a 24 pin can not be used in a 20 pin socket.

[HarryM1BYT]

An update....

I never like to dive straight into problem solving, without a bit of simply seeing how it goes first - if possible.

What I have found in the weeks since the problem suddenly developed was - if I switched it on and simply left it on for ten minutes or so, then shut it down and tried a restart, it would start up.

So last week I took the PC out to have another good look at it and see if I could find any failing electrolytics. No obvious failing ones on the motherboard or the sub boards, so I pulled out and opened up the PSU. No obvious visible problems there, so whilst that was opened up, I gave it a good clean out with an airline.

Since blowing out the PSU instead of having to turn it on and waiting 10 minutes before trying again, it will fire up at the second attempt without needing the 10 minute delay.

As said, I only blew the dust out of the PSU, so the problem is pointing towards the PSU. While the PC was out on the bench again, I took the opportunity of rechecking all of its output voltages and all were good.

I also checked the PG (Power Good) signal from the PSU with the scope. From what I could see, the PG signal is going high almost instantly, whereas as I understand it, it should remain low for a fraction of a second to delay the PC from trying to boot until everything has settled.

A bit of online checking of PSU's suggests my PSU is after all one of the standard ATX varieties, so when I do eventually get fed up of switching it on and off twice to get it to boot, I'll treat it to a new PSU

[HarryM1BYT]

Originally Posted by ukmoobs

There are 2 types of ATX psu there is a 20 pin and 24 pin make sure you buy the correct ATX psu a 20 pin can be used in a 24 pin socket but a 24 pin can not be used in a 20 pin socket.

My m/b has a 24 pin socket, but the PSU plug has only the 20 pins - leaving 4 pins unconnected. I actually thought an ATX PSU was an ATX PSU, but they do vary quite a lot. Some lack the SATA power plugs, some lack the 4pin plugs, some lack the 6pin plugs, some have the 240v loop through outlets on the back.