Associate
- Joined
- 16 Jan 2011
- Posts
- 21
Hi, for the last few months my pc hasn't been powering up immediately after the mains power is switched on. It started needing around 5 minutes before it would come on then after a while it got to an hour, now it's taking 2 hours + before it will switch on, otherwise it reamins dead. I've tested the PSU by shorting out the power on relay and it switches on. But when connected up to the rest of the pc it fails to start. I've figured the only two possible things it can be are:
1. The switch on the front of the pc.
2. Motherboard
now thats assuming the PSU is OK. I'm unsure of how the motherboard interprets the Power On pin but I assume when the pc is off and mains power on, then the switch recieves all power until a contact is made and then the motherboard is in control of that function as the switch is only making contact momentarly (otherwise it would go off again). So this makes me think it is a motherboard problem and it is somehow not making a closed circuit for the PSU to switch on. It is although something seems to have to "charge up" before it will power up and with time it's taking longer to "charge up" so this eliminates the actual switch as the cause, but not the actual switching on the motherboard. It will also take longer to power up if the switch is being pressed repeatedly as if it is draining this charge but it is not enough to power up as the PSU does absolutely nothing other than remain dormant or eventually switch on.
It is getting an old pc now although the motherboard is only around 2 years old the PSU is more like 6 years, so would be more inclined to think it was the PSU but it works when the Power On pin is shorted, leaving only the motherboard as the root cause.
Does this sound about right? Anything that I havent thought of or does anyone know more about the functioning of the motherboard regarding the Power On pin? Does it have a chip to control the PSU power?
Thanks.
1. The switch on the front of the pc.
2. Motherboard
now thats assuming the PSU is OK. I'm unsure of how the motherboard interprets the Power On pin but I assume when the pc is off and mains power on, then the switch recieves all power until a contact is made and then the motherboard is in control of that function as the switch is only making contact momentarly (otherwise it would go off again). So this makes me think it is a motherboard problem and it is somehow not making a closed circuit for the PSU to switch on. It is although something seems to have to "charge up" before it will power up and with time it's taking longer to "charge up" so this eliminates the actual switch as the cause, but not the actual switching on the motherboard. It will also take longer to power up if the switch is being pressed repeatedly as if it is draining this charge but it is not enough to power up as the PSU does absolutely nothing other than remain dormant or eventually switch on.
It is getting an old pc now although the motherboard is only around 2 years old the PSU is more like 6 years, so would be more inclined to think it was the PSU but it works when the Power On pin is shorted, leaving only the motherboard as the root cause.
Does this sound about right? Anything that I havent thought of or does anyone know more about the functioning of the motherboard regarding the Power On pin? Does it have a chip to control the PSU power?
Thanks.
