PC not powering up - Antec 1650b & Asus K8V-X SE motherb

[may1hem]

I've just fit together the component of my new PC and when I press the power button nothing happens. Can anyone help?

Here are the components of my new PC:
- Antec 1650b case (came with a 350w power supply),
- Asus K8V-X SE motherboard,
- AMD Sempron 2600 socket 754 (own sink/fan),
- Corsair 1Gb DDR ram,
- Maxtor 300Gb hard disk,
- ATI Radeon 9250 video card,
- Ebuyer firewire/usb PCI card.

When I plug the PC into the mains, then flick the power switch on the back of the case to the on (1) position then a green light comes on on the motherboard.

Then when I press the power button on the front of the case nothing happens. The power supply doesn't make any noise, the power supply's fan doesn't spin, the CPU's fan doesn't spin, the case fan doesn't spin, the hard disk doesn't power up.

I guessed that the motherboard must be receiving power as the green light comes on. I wondered if it was the power switch cable which connects to the motherboard, so I took out all of the LED cables & the speaker cable and left in just the "POWER SW" cable and the "RESET SW" cable. Tried to power on but again nothing.

I think I should mention that the power supply has a 24-pin cable for the motherboard, but the ASUS motherboard has only a 20-pin socket. However it plugs in just fine, leaving 4 of the pins hanging unconnected off the end of the socket. Could this be a problem?

There's also a 4-pin cable coming from the power supply which I plugged into a matching socket on the motherboard. I think this is the Aux Power cable and I think I read on the web that this must be connected for the Asus motherboard to power up. Well I've connected it but no power up.

Can anyone help me? :?

Thanks,
May

 

[krazyIvan]

Two things off the top of my pointy head; clear your CMOS, and double check your 24 pin connector is plugged completely into the MB. I had a similar problem with a system I just put together and it ended up being one of the 24 pins wasn’t seated fully into the plastic Molex connector from the PWSP and didn’t make good contact when inserted into the MB.

Also if you have a millimeter, test the power sw., and double check you’ve plugged the two pin PWR SW connector into the correct header.

 

[krazyIvan]

And yes, you can plug a 24 into a 20. just make sure the pins that are used line-up with the ones that are needed (you might have to compare your PWSP manual with your MB manual).

And yes the AUX connector is often used; it should be two black and two yellow wires.
Not to be confused with the P4 aux connecter, which has different colored wires, unless you’re using a P4?

 

[may1hem]

Thanks for your suggestions, krazyIvan.

1. Yes I've cleared the CMOS,
2. Yes I checked the 24-pin, took it out & plugged it back in,
3. I don't have a meter,
4. Yes I've check the PWR SW connector, also tried rotating it 180,
5. Ok I've checked the 24 is lined up with the 20,
6. Yes, AUX has 2 x black and 2 x yellow. I'm using AMD Sempron.

Nothing has changed at all. Still nothing but the motherboard green light. No fans, no sound, no movement.

Any other thoughts?

Thanks,
May

 

[Vascular]

Also check the back of your power supply and make sure you have it on the 115V and not the 230V.

 

[krazyIvan]

The green light on the MB is a safety/standby indicator, it reminds you that even thou the power SW is off, the MB still has power and you should be careful messing around in it. One of the lines on the 20pin supplies a standby power that powers among other thing a ckt that operates a turn-on signal to the power supply. I have seen threads on other sites about problems like yours. I don’t remember what the resolution was, but there was one. You might go over to the ASUS website and search through old threads to see.

Hear is a web site with some helpful ideas;
http://www.computerhope.com/issues/ch000312.htm

 

[krazyIvan]

Another good info site, but without a multimeter, it may not help.

http://www.bluemax.net/techtips/ATXPowerSupplyWiring/ATXPowerSupplyWiring.htm

 

[may1hem]

Thanks for this. It's working now.

You know what the problem was?

I put the power switch cable on the wrong pins. Doh! I don't know how, as I checked it like 10 times.

Thanks for your help,
May

 

[krazyIvan]

Trust me home builders could fill the National Archives with tails of "Ooops!"