So I've bought all these parts to build me a gaming machine   and around my friends house I assembled it and tested it. I didn't have enough time to install windows, but by the time I left I had got as far as getting DOS up etc so I know everythings working.

I take it hoem and reassemble it, however my monitor shows nothign but black. I try a few times using TWO different monitors just to check it is actually the computer, which it seems it is.
After thinking about it for a few days I attempted to try using a diffrent harddrive, mine may have got damaged on transit. But then this time the power doesnt even turn on! The CPU fan will not even move.

At a guess, I take it my motherboard is at fault?1) If you didn't have time to install an OS how did you as you say get DOS up ?
2) If you assembled it at your friends house why did you have to re-assemble it when you got home ?
3) Why would you think the HDD got damaged in transit ?
4) Have you tried to install an OS yet ?1))Oh oh I mean BIOS My bad  

2)I took it APART because I dotn have a proper case for it

4)Well no, on account it doesnt start up.When you say you don't have a proper case, you mean you just got all this electrical stuff laying around the kitchen table plugging it up or what? I know a lot of people laugh at static electricity but it can be a problem. What are you useing for a power switch? Have you checked the header pins to make sure the switch is connected right? I have more QUESTIONS but I will give you time to answer these.Did you take ESD precautions?
Did you install the LPS modules?
Pull it apart & put it back together again. (Carefully).
If it still won't start swap the PSU.Without a case i personally would quit screwin around before some/all expensive components are ruined... The actual motherboard is screwed onto the raised plate of metal that would slot into a crappy dell case. the motherbord is also sitting in it's own shelf that I salvaged from that awful case.

To turn it on, I have the normal switches. I just dont have the actual button over the top from a case. Actually it is possible they were not in properly, maybe they have been pulled out so I will have to try putting them in again. But I do think when I tried them that there was a sound I HEARD. It was like....the sound of a monitor turning on but less of a blink sound and more of a groan sound..if you can understand what I mean?
Then when I press the switch again no sound is heard unless I unplug a few things replug and try again.

When we were assembling this, although I dont really believe in them, we did have rubber gloves and all sorts of anti static things to stop that happening.