Problem With Power Supply Unit

[Dharamsi]

Well i have a power supply when its installed in the computer it wont turn on. the power supply unit is of zalman. I don't get the real problem or cause behind this

Please provide some views regarding this

[deoWo]

That's not static you hear, that's mains sparks flying as you disconnect the power from the mains. Always switch off from the wall socket first!

You're probably aware that the on/off button on the front of the computer does not actually do anything other than signal the power supply unit to switch on or off. So if there's a problem with switching ON only (ie it will always switch off gracefully when you hit that button) then the problem is to do with your mobo/PSU.

When you unplug then you really are shutting things down properly. Many mobos are kept alive and running when connected to the mains unless the power is actually off at the socket. That's why you must always switch off properly before replacing PCI cards, processors etc!!

Try switching off at the wall socket regularly and see if it always come back on line when you then boot up...

[RoninBlade]

this problem can also be caused by a power supply that has a weak standby current. the mains voltage may have dropped a bit due to high demand in the hood, and the standby current that was already weak drops to a level that the mother board cannot recognize. the standby current is always supplied to the mother board even when it is off, when you press the power button it lowers the voltage on the standby pin to ground signelling the power supplie to power up the main power. to many pci cards in a system that use the standby voltage eg. wake on lan nics and some video cards, ps2 mice and keyboards, can drop the voltage to much and stop a pc from powering down or up.
try and get a power supplie that has a larger standby current

[Fabian]

I have this exact same problem, ever since I bought a new case with a new powersupply in it, I have to completely turn off the power and unplug the cord and re-plug in back in again before it will turn on. I had no problems at all with my old case and PSU, with the same mobo. My friend said the same problem happened to him, and he started using a different Power Cord to the PSU and it fixed the problem. I found a different cord, and the computer powered on and off twice perfectly before reverting back to its regular habbit. It may have been a co-incedece that at this time people were using less power in my area or something. There are two things I dont understand though, 1. Why is this happening when the PSU I have in my case is meant to be a top of the line model. and 2. Why would it somehow work for a bit by changing my cables? Arent all cabels the same?
Well thats my gabble, reply if you know a solution to my problem, besides buying a new PSU

[Hardwareman]

I have a problem which sounds similar to what many of you describe. At first, I could just turn off the pc and then turn it on again and everything would boot normally. As time goes on, it has become more and more work to get my machine to post.

Tired of the problem, I slapped a troubleshooting card into a pci slot and discovered that the 3volt standby power led was not showing any power. After a couple of resets, I start to see a light pulsing which then builds to solid green over the course of a few minutes. When the led is fully lit, I can turn off the computer, turn it on again, and watch it boot.

My inclination, at this point, is to suspect the power supply. I'm also inclined to believe that some, or all, of you are assuming your machine started after changing the power cord. I can see no logic at all in this line of thought, and my little LED tells me otherwise.