PSU issue

[jamesgoddard]

I have an issue with getting my PC to start, it will not power on unless the power input at the wall socket is turned off for 5 seconds, and then I hit the power switch, does this look like a PSU issue???

Any recommendations or shall I just RMA the PSU....

 

[turpit]

Thats unusual. It could be something weird with the PSU, but Ive never heard of anything like that. It sounds like it may be a bios or bios battery problem. There is always power going to the mobo, even when the system is off. When you kill the power to the PSU, you remove all power to the system, allowing the capicitors to drain. At that point, the only thing holding the bios memory is the battery. If the battery is shot, the bios will reset to default (for what ever version you have) and any changes made to it will be lost.

 

[jsc]

I would try swapping out the PSU first. There is a surprising amount of internal checking of the PSU before it generates something called a "PSGood" signal. This must go "Logic High" before the CPU can start the boot process.

Although I also have never seen this, it is possible that something in the PSU is stopping the "PSGood" signal unless the PSU starts from a completely OFF state. I am curious. Do the fans spin up even if the system doesn't boot?

The first obvious sign that the BIOS battery has failed is that the computer forgets what time it is after having been turned off. Loss of configuration data is usually more subtle. A bad or missing battery should not prevent a PC from booting.

john

 

[Onus]

Sounds like a bizarre PSU problem. When you shut down, it triggers an overload condition, which is cleared by the complete power-off, allowing it to restart. How old is it? What brand and model?

 

[Hawkeye22]

My old PSU would do this on an overload condition. It was fine for 18 months, but I think the components wore out over time and it could no longer supply the necessary power. It was an antec truepower 450w that came with my Antec Sonata II case.

 

[jamesgoddard]

How old is it? What brand and model?

It's a 10 month old Antec TPII 480W, and the system load will be way under that (ATI 1950pro, P4 631, 2GB RAM, 1 x HDD and 1 x CD)

 

[clue69less]

My old PSU would do this on an overload condition. It was fine for 18 months, but I think the components wore out over time and it could no longer supply the necessary power. It was an antec truepower 450w that came with my Antec Sonata II case.

18 months is about typical for that PS if it's loaded to a reasonable level, like say 70%. You might get 3 years out of it if you're lucky but really, it makes a better anchor.

 

[Hawkeye22]

18 months is about typical for that PS if it's loaded to a reasonable level, like say 70%. You might get 3 years out of it if you're lucky but really, it makes a better anchor.

Yeah, and running it 24/7 didn't help it any either.

I replaced it with a Seasonic S12-550w.

 

[Onus]

It's a 10 month old Antec TPII 480W, and the system load will be way under that (ATI 1950pro, P4 631, 2GB RAM, 1 x HDD and 1 x CD)

Warning: unsubstantiated opinion ahead

I wish I could remember why, but something "bothers" me about Antec PSUs; always has. A lot of people I trust like them, but I don't think I'd ever buy one.

[/fud]

Anyway, I think you ought to try a new PSU.

You might also try resetting your BIOS to default; maybe it is some kind of suspend/wakeup issue getting cleared only when the +5vsb dies.