PC turns on every time, how to fix it?

Question

Iron

PC:
MB - Asus M4A79 Deluxe, CPU - AMD Phenom II X4 940, Power supply - Ascot Silent Pro A-620 620W, GPU - NVIDIA GeForce GTX 580 (from Asus).
When you press the power button (every other time), the computer turns on for 0.1 seconds and turns off (subsequent presses do nothing). You have to turn off the power supply and turn it on again, and wait ~ 5 minutes, and then press the power button to make it work. During operation, everything is stable, no issues.