Cant boot computer

We need more information.

Maker and model of every part to start with.

Also, we need to know what you see and hear when this is not booting. Do you see/hear fans coming on? Does it come on and go right back off and stay off? Does it turn off and on repeatedly?

Without more data we really can't even begin to assist. Also, don't bump your post, it looks like we already answered you if you do.