So I have an HP Pavilion a1600n computer case that I'm gutting for my first build. It has a 300W power supply that I want to replace with an FSP 450W PSU, but I'm unsure of the FSP will fit. I've searched everywhere I could to find a definitive yes or no answer and to find the deminsions of the currently installed psu for a comparrison but its tocno avail. Any insight on this?