Connection problem

Strange problem but will explain as best I can. When I switch my PC on it sometimes goes on & back off immediately, now if I leave it for a bit and try again usually the same thing happens,however, if I pull the mains lead at the back of the PC and leave for a few minutes then go back and push in the mains lead and then switch on then this usually works and the PC boots up. If it doesnt I go through this process until it does. I cant see a loose connection at either the mains input to the pc or the on /off switch for the tower. (but me not electronically qualified) Now the other day I thought maybe I could swap the on/ off switch from an old PC, it wasnt compatible however by accident I then discovered if I connect my external (back-up) hardrive via a USB which is at the front of the PC it boots the PC up so therefore by passing the above issue. Now this is great as it means I can now boot up without the hassle, however, something is obviously not right so trying to get to the bottom of it. The PC is probably 7 years old but apart from this issue it serves purpose. Any help with this would be appreciated. thanks

Hi Scudo, This is a common situation especially with computers that are not in their first flush of youth….. Some of my customers find that they can switch on their computers merely by powering up their printer….( one connected by USB) Even though the computer may be powered down there is still electricity going to the the motherboard…until the mains power lead is pulled out or if there is an extra power switch at the back of the computer and it'sswitched off there. It's a tricky situation for a computer repair tech as its a fault that should be remedied, and best advice is to decommission the machine correct the fault (its usually a fault from power on switch/wiring) If I happen to have the correct power on switch in my "bag of spares" that will fit the computer concerned…. then fine…. it's an inexpensive repair and worthwhile to do….. However trying to find the correct switch, if I haven't got one, (if it is the switch that's faulty) ordering it. (a 7 year old computer power on switch may not be readily available) and then a home visit to fit…could result in either a tiny bill or a very large one….( effectively making the machine beyond economic repair)… I can't recommend to my customers that they leave things as they are….. the best advice must always be to make sure that anything electrical is 100%……….. but I can understand why folks put up with it! Regards paws