Power supply prob ( no juice)

car147 · 07-10-2008, 11:44 PM

Hi

a bit stumped with this one, a mate asked me to have a look at his PC which has never worked since he got a friend to build it for him.(feel sorry for him as it cost nearly a grand awhile ago).

When you turn it on there's nothing apart from a red led lit in the psu, and 2 leds lit steady on the mobo, no fans, no cpu fan or sign of life.

The mobo's a Abit kn9s and has a 24 pin atx socket, psu's a X-power 450 w but states on it pentium 4 ready?

the mobo pin outs for atx power are 24 pin, this power supply comes witha 20 pin plus the four pin, but the wiring looks different on the 4 pin psu lead, are these different for AMD, and Intel set ups? are there differing voltages on the pin outs, if so this guys possibly fried it

any info appreciated

car147 · 08-10-2008, 10:17 AM

PSU changed, still the same, so i guess the M/B's shot or cpu? any help would be appreciated.

Big B · 08-10-2008, 01:22 PM

I can see where you're confused. A 24-pin PSU may have some of the block removeable for compatibility on older 20-pin boards. The 4 pins that come from here are a little different from the auxillary 4-pin block that are on motherboards. They do not differ between Intel and AMD platforms, but the P4 ready part comes from the days when the P4 was new and required more juice on the +12V rail.

I'd start by taking the motherboard out of it's case and placing it on a flat, non-conductive surface. This way you can eliminate any possible shorts coming from inside the case. Have 1 stick of RAM, the CPU and heatsink, video card and the PSU installed. Make sure that all power connections on the motherboard are plugged in.
You can use a flat-headed screwdriver to short out the pins on the motherboard's front panel connectors to start up this configuration.

The reason you want to go down to this barebones configuration is to eliminate as many possible problems as you can.

As far as parts go, what exact parts do you have?
What symptoms was the system having prior to it's inability to turn on?

car147 · 08-10-2008, 06:00 PM

Thanks for the reply, luckily i have a friendly local supplier so he lent me a psu and mobo, turned out it was the m/board after all, now running sweet.

07-10-2008, 11:44 PM	#1 (permalink) Top
car147 Geek Trainee Join Date: Jul 2008 Posts: 3 Status: Offline	Power supply prob ( no juice) Hi a bit stumped with this one, a mate asked me to have a look at his PC which has never worked since he got a friend to build it for him.(feel sorry for him as it cost nearly a grand awhile ago). When you turn it on there's nothing apart from a red led lit in the psu, and 2 leds lit steady on the mobo, no fans, no cpu fan or sign of life. The mobo's a Abit kn9s and has a 24 pin atx socket, psu's a X-power 450 w but states on it pentium 4 ready? the mobo pin outs for atx power are 24 pin, this power supply comes witha 20 pin plus the four pin, but the wiring looks different on the 4 pin psu lead, are these different for AMD, and Intel set ups? are there differing voltages on the pin outs, if so this guys possibly fried it any info appreciated

08-10-2008, 01:22 PM	#3 (permalink) Top
Big B HWF Godfather Join Date: Dec 2001 Age: 28 Male Posts: 9,640 Times Helpful: 585 My Mood: Devilish Status: Offline My Computer	I can see where you're confused. A 24-pin PSU may have some of the block removeable for compatibility on older 20-pin boards. The 4 pins that come from here are a little different from the auxillary 4-pin block that are on motherboards. They do not differ between Intel and AMD platforms, but the P4 ready part comes from the days when the P4 was new and required more juice on the +12V rail. I'd start by taking the motherboard out of it's case and placing it on a flat, non-conductive surface. This way you can eliminate any possible shorts coming from inside the case. Have 1 stick of RAM, the CPU and heatsink, video card and the PSU installed. Make sure that all power connections on the motherboard are plugged in. You can use a flat-headed screwdriver to short out the pins on the motherboard's front panel connectors to start up this configuration. The reason you want to go down to this barebones configuration is to eliminate as many possible problems as you can. As far as parts go, what exact parts do you have? What symptoms was the system having prior to it's inability to turn on? __________________ Hardware Forums\|HWF Rules\|My DVD's\|PSU FAQ\|HWF Folding Team\|2CPU

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08-10-2008, 10:17 AM	#2 (permalink) Top
car147 Geek Trainee Join Date: Jul 2008 Posts: 3 Status: Offline	PSU changed, still the same, so i guess the M/B's shot or cpu? any help would be appreciated.

08-10-2008, 06:00 PM	#4 (permalink) Top
car147 Geek Trainee Join Date: Jul 2008 Posts: 3 Status: Offline	Thanks for the reply, luckily i have a friendly local supplier so he lent me a psu and mobo, turned out it was the m/board after all, now running sweet.

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