I replaced my power supply recently and I now have the following problem: The PC powers up and works great but when you power down the PC won't boot again unless you leave it off for two hours (yes, really!).
This has been driving me nuts for the last couple of weeks. I've swapped out all the components I could with another working PC and I still get the same problem - the fans all power up, the hard drive spins, the CD powers up and the front panel lights light up as normal then just a blank. If I power down and leave it for a couple of hours (one isn't enough) then it boots OK.
Could it be a component (a capacitor?) that isn't draining when I power off (via the front panel switch or soft-off). Control ALT Delete boots work fine though when it's running. The motherboard is an ECS KZVZA and I've not had any problem before this. However I'm coming to the conclusion that when the old power supply died it wasn't the only thing that was damaged.
I thought initially that overheating was the problem but the it occurs before the PC has any time to generate any real heat i.e. boot it in the morning and then power it straight down after Windows has loaded and then I can't boot without waiting about 2 hours. It can't be the hard disk pre-delay as I've stripped the motherboard down to just the graphics card, one memory stick and the floppy drive and keyboard. All these components work in another machine. I've also loaded the BIOS defaults and turned of quick booting. I've changed the CMOS battery. I've also re-flashed the BIOS.
I have tested the power supply in another PC and it works fine although I haven't tested another power supply with my motherboard as I can't get hold of one yet. So it might still be the power supply.
I think I've just about run out of ideas on this one. One thing I did notice is that the keyboard CAPS light stays on after power down (I thought that the power would go off to the keyboard?). Also the CMOS is holding the settings I give it and will attempt to start up if I set an alarm. This indicates that the BIOS is working OK although there is the possibility that it might be partially scrambled I suppose.
I still can't understand why waiting a couple of hours allows me to boot OK.
Does anyone have any ideas about this?