computer wont boot up

[booty]

Hi all ive just bought a new motherboard, cpu, and video card which are:

ecs rs400a lga775 atx motherboard
pentium 4 640 3.2 gig
radion x1650 pro video card

ive put on there 768 meg ram.

I connected all the cables and put it together then booted it up.

The computer starts the cpu fan runs, the graphics card fan works, the dvd drives open but it doesnt boot up and the monitor stays on standby.

Can anyone help?

Cheers

[patio]

A bit more info...
Any beeps at all ? ?
Did you use thermal paste when assembling the CPU ? ?
Is this a new PSU or your old one ? ?
Did you remember the 4 pin power connector to the MBoard ? ?

[booty]

Hi

there are no beeps,

didnt use thermal paste but there were gray paste on the heat sink so i thought that was it

the psu is old

where is the 4 pin connector from cant remember if i did connect it?  i will have a look when i get home!

cheers

[patio]

We'll keep the light on...

[booty]

Hi i changed the motherboard and it works

It recognises the cpu, ram, and the dvd drives then it shuts down

Whats the bloody matter machine with it?

Can any one help because i want to chuck it through the window!

[patio]

MBoard shorting on the case...
CPU fan not installed properly...
Inadequate or failing PSU...
RAM not seated properly...
ETC. ETC.

It can be quite a few things as you can see.
Try it with just the bare minimum: 1 stick of RAM, video card, CPU, fan, mouse keyboard and monitor.

Then add one item at a time until you find the culprit.