First computer build- nothing happens

[kbedson]

Hi everyone,

This is my first attempt at building a computer, so I really hope I'm overlooking something simple, and won't have to replace any faulty components. Basically I connect the computer to the power supply and the motherboard power light comes on- but nothing else happens, the fans (including the PSU fan) don't spin and almost no power is coming out of the molex clips. I read somewhere that with an ATX board the motherboard controls the PSU so my first question is, based on the fact the powerled on the motherboard is on- can I assume that there is nothing wrong with my PSU- and that the fact that almost no power(0.4v out of yellow & 0.2 v out of red wire) is coming out of the molex clips is due to the motherboard sensing something wrong with one of the main components (CPU, RAM) or itself being damaged- which stops it from activating the power supply? I've placed the motherboard on a book so it shouldn't be shorting out.

specs
pentium 4 2.8Ghz dual core 775
Asus 775 865 AGP DDR
Kingmax DDR512-400 PC3200
ATX tower case 400W
Maxtor 80GB SATA HDD

thanks for your help,
Kim

[Kov-Ice]

Welcome to PCMech. What make/model PSU are you using? Do you have access to a known good one that you could swap in and try?

[sgtspector]

It is possible you may forgotten something in your assembly. Have you connected the 2 x 2 cpu power connector? It could be anything. If you haven't done so already try this procedure. It will help isolate a missed step or faulty component.

[Cricket]

Originally Posted by kbedson This is my first attempt at building a computer, so I really hope I'm overlooking something simple, and won't have to replace any faulty components. Basically I connect the computer to the power supply and the motherboard power light comes on- but nothing else happens, the fans (including the PSU fan) don't spin and almost no power is coming out of the molex clips.

If all you did was connect the power supply power connectors to the motherboard and then plugged in the power cord to the wall outlet then all you will get is the motherboard LED turning on, nothing else. You haven't started the system up yet.

Originally Posted by kbedson I read somewhere that with an ATX board the motherboard controls the PSU

Yes, to start the system a signal from the motherboard must tell the power supply to start sending full power to the system. You do this by either connecting the power button connector to the proper pins on the front panel header and hitting the power button to start the computer, or you can use a small screwdriver to jump the two PWR ON pins on the front panel header momentarily.

Originally Posted by kbedson based on the fact the powerled on the motherboard is on- can I assume that there is nothing wrong with my PSU-

No...all the LED on the motherboard is telling you is the motherboard is getting standby power from the power supply...it doesn't tell you that the power supply is working 100% correctly.

Originally Posted by kbedson and that the fact that almost no power(0.4v out of yellow & 0.2 v out of red wire) is coming out of the molex clips is due to the motherboard sensing something wrong with one of the main components (CPU, RAM) or itself being damaged- which stops it from activating the power supply?

Until the power supply gets the proper "power on" signal from the motherboard you won't get anything coming out of the molex connectors.

Originally Posted by kbedson specs pentium 4 2.8Ghz dual core 775 Asus 775 865 AGP DDR Kingmax DDR512-400 PC3200 ATX tower case 400W Maxtor 80GB SATA HDD

Those are not complete specs. There is no Pentium 4 dual core processor...it's either a Pentium D or a Core 2 Duo...or it's not a dual core but a single core Pentium 4. Which model ASUS motherboard are you using? What brand is the power supply? What about the video card and the drives?

Cricket

[flanzig1]

From your basic discription of the motherboard, sounds like it's a transition board for AGP and socket 775 like the Asus P5PE-VM.

[kbedson]

Originally Posted by Cricket Yes, to start the system a signal from the motherboard must tell the power supply to start sending full power to the system. You do this by either connecting the power button connector to the proper pins on the front panel header and hitting the power button to start the computer, or you can use a small screwdriver to jump the two PWR ON pins on the front panel header momentarily.

funnily enough I completely forgot about turning the computer on! thanks for pointing this out and saving me from a very embarrassing trip to the repair shop. The fans are spinning and now it looks like everything is working as it should.

Originally Posted by Cricket Those are not complete specs. There is no Pentium 4 dual core processor...it's either a Pentium D or a Core 2 Duo...or it's not a dual core but a single core Pentium 4. Which model ASUS motherboard are you using? What brand is the power supply? What about the video card and the drives?

ok, let me try that again

Asus P5PE-VM motherboard
Pentium D processor 2.8 ghz
Kingmax DDR512-400 PC3200
USIcase ATX tower case with power supply 400W
Maxtor 80GB SATA HDD
Samsung 18xDl Dvd-r/+r/rw

and the motherboard comes with Intel Extreme Graphics 2- which I was planning to trial before deciding whether or not to buy a video card.

thanks for your posts, I'll be sure to let you know if anything else goes wrong
Kim