text: what is the actual reason why do cpus wont start.  good monitor and its cable... cpu dont display cmos startup upon switching on the cpu... the monitor displays monitor is enabled and with signal.... but after that no actions on cpus... power supply is on.... hardisk lights on... but no cmos reaction... rather no displays of cpus at all... first of all, it's not a display of your cpu. it's you powering up your system.  it could be a number of scenarios: 1. something is wrong with your ram (a good indication of this is if your computer beeps as soon as it starts up and a blank screen remains). 2. your motherboard could be fried (odds of that are low since you claim to have monitor signal, revealing that your video card is fine). 3. your cpu is fried. only real way to check this is to find another motherboard compatible with your cpu and test it. 4. your cmos battery is dead. replace it.  from my past experience, #3 and #4 are your most likely scenarios in this case. hopefully it's only #4 that's the problem.  good luck.