My pc was booting fine earlier and has been since i built it, apart from it freezing at starting windows but that's not to do with this.
Anyway, my pc was looking pretty neglected so i decided to clean it, remove dust from everything, reseat all components and move wires for better air flow, so i did. Also i took the CMOS battery out and put it back. Everything is in place as it was..

I've turned it on and everything is running, fans, gpu, cpu etc... but i'm getting nothing on my monitor(s), not even bios. i've tried the onboard graphics, but still the same problem. There are no beeps when i boot but it's always like that. I've looked into it via google but havent found a solution, my motherboard is okay because i took out the ram and it beeped. Also i've got my keyboard plugged in to try and get into bios, but there seems to be no power going to it, and also it doesnt sound like the hard drive is doing anything. Not sure what to do, help me please!

Thats 'funny' to see. I had exactly the same problem as you when I cleaned my PC. I couldn't get any screen, no matter what GPU's I used.

After a day of trying I swapped the mobo and CPU that was in it with the ones from my old PC, which made it work again. So I thought my mobo was fried or something. However, when I swapped my old CPU in the new mobo, there was also no screen. So I think it's my CPU as everything is working now with another CPU.

The strange thing is that my new CPU works on the old mobo...

Without further hijacking your thread, could you try to swap some hardware?

hmm weird, i think i can as my dad owns a computer shop, but i can't always go there as he doesnt live here and the shop is far away.

what an annoying problem, sometimes i hate technology..

edit; just tried the mouse and it works, but the keyboard doesnt... i'll try another kb

edit edit; other keyboard doesnt power up either

What do you mean 'it works'? Does the light on the kb/mouse lit op or something?

It can be anything from a faulty PSU to a mobo, kinda hard to say.

Do you hear the beeps of the POST?

never hear post beeps but i hear error beeps, and yeah, the mouse lights up but the kb's dont. Right now i'm trying to get my intel fan in, it doesnt want to click on all 4 things and it's pretty damn annoying.
They can't be faulty as my pc was working fine before this?!

Problem solved! Along with my problem where my pc would freeze at 'starting windows' and i'd have to wait 15 mins for it boot.
I took out my gpu and started my pc, i then got 3 beeps which i had a look about and it was my ram, so i moved it to another slot and cleaned it, put my graphics card back in, and also removed + cleaned the CMOS battery. Just like that it's working again!

But, my graphics card isnt being detected, i've reseated it and cleaned the slot and it's still not being detected, any help?