My computer turns on but. My computer turns on but wont turn hdd all the way on it starts then

Question

My computer turns on but wont turn hdd all the way on it starts then clicks and stops goes to a black screen. and there is a smell coming from the computer. i put the hdd in another tower and it worked.. so my question is i have a Okia ATX300 and need to replace it...but haveing trouble finding one. can i buy one with more watts as long as the plug fits