I cannot start my PC by pressing power button

Please someone help me solve my pc power problem. Whenever I want to start my PC, I press the power button of system unit but it failed to boot. Although it seems work, it cannot show the boot screen and then when I press the reset button, the pc is boot. So whenever i want to start my pc, I always need to press both Power button and reset button, I think that it is power supply problem. If anyone who know this problem, please kindly help me. Thanks you very much.
 
Open the case and make sure the inside of the computer is clean and free of major dust and debris. Check the motherboard connections to the front panel switches. Lastly replace the power supply...
 
Back