Computer won't start. HELP!!!!

[bowloffat]

OK, so I bought a new compter at Best Buy early July. I also bought a couple of components for it, power supply, ram, graphics card. By the time the graphics card came (I bought it online) it was August past the return policy of 30 days at Best Buy. I turned on the computer, did the initial set up and then turned it off to put the other stuff in. I put it all in and now the computer turns on for a good second and then turns off. Sometimes it doesnt even do anything. Nothing ever pops up on the screen. It doesn't ever reach that point. Now I could send it away to HP to get it fixed but I am going off to school in two weeks and it would take much longer then that for HP to fix it. I probably will take it to Best Buy to get it repaired probably costing like $100. I have tried all I can do myself and am asking for any other ideas so I don't have to become poor for my computer to work. If anyone can give me any kind of help whatsoever I would be very thankful.

 

[Atomic Rooster]

First make sure all cables, power connections, video card, memory, etc. are all fully seated and installed properly.

 

[Tommy Boy]

It's most likely the power supply that is bad. BTW, why did you buy a new power supply for a brand new computer?

If it worked before, I'd just put the old power supply back in.

 

[Bob94571]

are theyre any beeps when it shuts of or when you turn it on?