strange PSU problem

[wxiao]

My computer died, and I have pretty much narrowed the problem down to the PSU. I noticed something weird about the PSU: when the power cord is plugged in, and the PSU is NOT plugged into the motherboard, the PSU green LED is on. Immediately after the PSU is connected to the motherboard, the LED goes off. Is this normal? Any indications of the kind of problems it has? Thanks.

 

[mpilchfamily]

could be a bad motherboard but we need some more info here. How about listing your system components and give us some more detail on what its doing.

 

[wxiao]

Thanks for the reply. Here is what happened: the system died a couple of weeks ago. My first guess was that the PSU was dead. But using the a paper clip, I was able to power the PSU up. My next suspect was the motherboard. I installed a new motherboard today. Still no luck. With the 12v ASX connector of PSU inserted onto the motherboard, I can even power up the system by inserting the paper clip into the 24 pin power connector of the PSU. But when I pressed the normal power button, nothing happens. So my next guess is that the power button of the case is faulty. I tried to short the two "power-on" pins on the motherboard to boot up the system, no luck. This was when I realized the strange PSU problem that I reported in the first post.

 

[johnnydrinkawater]

The LED could be an warning indicator telling you to unplug the PSU from the wall before plugging it into an components. Have you noticed that before?

I know my mobo has that feature as a warning to unplug the PSU before messing with anything seated in it.

 

[wxiao]

The LED could be an warning indicator telling you to unplug the PSU from the wall before plugging it into an components. Have you noticed that before?

I know my mobo has that feature as a warning to unplug the PSU before messing with anything seated in it.

Well, it could be. But even if I plug in the PSU first, and then to the wall, the PSU light is still off, and system does not boot.

 

[johnnydrinkawater]

Well, it could be. But even if I plug in the PSU first, and then to the wall, the PSU light is still off, and system does not boot.

I'd say either a MOSFET or cap blew, but the LED circuit is still receiving some power. When a PSU is dead it's DEAD because of the current magnitude that runs through them. I'd say a replacement is in order.

 

[PsiStar]

So, it is *not* the m/b. And, from personal experience, I would definitely not be plugging a suspect PSU into the new m/b as you have no idea what may be coming out of it.

Without a voltmeter or a PSU tester, it is only a guess that the PSU has failed ... but it is the most likely problem ... versus a HDD, RAM, CPU ... etc. I still wouldn't be plugging it into the new m/b.

Go to Best Buy (or something like that) & pick up a capable PSU. Try it, if it works, order a good one from 'egg & make the return to BB.