Computer powers on/off, with no POST

[worldwise]

Hi all,

I just built a new computer and tried to power it up for the first time. It powers on (lights up / fans spin) for about 2 seconds and then it just powers off.

After 1 second it powers up again for 2 seconds and then powers off.

This repeats indefinitely until I turn off the PSU.

It never reaches the POST and the screen is blank the whole time.

Anyone have any ideas?

Thanks~

 

[tlcscousin]

power switch stuck could be one, take plugs off and try shorting the pins to see if it starts.

 

[worldwise]

Hi, thanks for that super quick reply.

How do I "short the pins" to get it to start.

 

[tlcscousin]

If you look at the pins on the motherboard where you put the power connectors just use a smail screwdriver and toch both those pins at the same time hold the screwdriver on the pins until it starts then take the screwdriver off the pins. If it keeps running then it would indicate a short in the power switch wires or a power switch stuck.

 

[worldwise]

Got it. Thank you.

 

[tlcscousin]

Let us know if that was the issue or not.

 

[worldwise]

OK so it turns out that 1 of my 4 sticks of memory was bad. Im running off 2 of my good ones and everything is fine. I'm in the process of loading Windows now.

1 quick question. Early in my build process i thought i'd try to boot up but the PSU wouldn't even turn on. I only had the PSU connected to 1 fan (nothing on the mobo or anything).

Does there need to be a closed circuit for the PSU to power up? Its a OCZ 700w GameXtreme brand new.

I since have put in another PSU unit and I'm too lazy to put in the OCZ one to test it again. I'm thinking of just returning it but don't want to look like a moron when they test it and see that its working fine.

Also, thanks so much for helping with this issue.

 

[BadBigBen]

Does there need to be a closed circuit for the PSU to power up?

Yes, but actually it needs a certain amount of draw on one rail (can't remember which one)...

Sometimes, the PSU needs to be reset, e.g. holding the power button down while the PSU is disconnected from the wall outlet...

Sometimes, when building a new PC, the mainboard needs to be reset, e.g. CLR CMOS, because it tries to set the specs for a CPU that you may not have installed, then it will notice that something is not kosher and behave the way you described...

Ben

"If it works don't fix it! If it doesn't use a sledgehammer..."

 

[edfair]

Power supply comes up from a power-on signal generated in the standby section of the motherboard. Requires standby power from the power supply to be to the M/B then the power up switch sets a latch the fires the PS and brings everything else up.

Shorted power up switch would generally do a 5 second cycle rather than your 2 second one.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[worldwise]

Sorry if I confused you edfair - the 2 second cycle was due to a bad stick of memory.

After I figured that out I kind of started a new, unrelated question about the PSU.

Basically I was plugging the PSU into the wall and connected it to 1 case fan only and it wouldn't fire up. But from the sounds of your post I guess it shouldn't have and that it actually needs to be connected to the motherboard to work.

So I got 2 questions answered in 1 post. Great!

 

[paparazi]

Simply put...YES! the power supply needs to be plugged in to the motherboard OR two pins (can't remember off the top of my head which two) need to be bridged in the main power plug....in order for the PSU to 'FIRE UP'. So this power supply is almost certainly fine.
Martin

On wings like angels whispers sweet
my heart it feels a broken beat
Touched soul and hurt lay wounded deep
Brown eyes are lost afar and sleep