Ok so now you are running Windows7 64bit again. Try not to alter things as each time you can bring in more variables to the equation. Please just try using a single stick of memory in the first slot and then remove any extra items that are not 100% required for the system to work. You should have just psu, mobo,cpu, hsf, ram, graphics, buzzer, hard drive, keyboard and mouse. Boot and see how things go.