i bought an antec 650W neopower blue to replace a crappy icute 350w power supply i connected it up and my computer started up fine. then i changed my cpu fan to a zalman flower cooler it then started fine again, but after tighting up all of the screws and closing my case up and starting it up agian my computer doesnt start. there is power to all of the parts as the case fans,drives ,cpu fan, motherboard light are all on, the lights on the front of the case for when you power on the system dont come on thought not sure why. so basically everything appears to be running but i dont get anything on my screen and case lights done turn on, my screen is still working by connecting it up to my laptop so that isnt a problem. i have already tried putting my old power supply back in just to be sure and didnt make a differance. Please help aint got a clue what is wrong!!!!!