I can`t start my imack
A few days ago my iMack shut down and I can't turn it on. When I press the button there is apple sound and apple appears, after 2-3 minutes the computer shuts down. No letter shortcuts, start from another drive, reset etc do not work. Nothing works. the computer does not want to start. I replaced the memory, tried with another processor and nothing. Please advise something. Motherboard?