Question PC no post, no beep,no signal to the monitor

[qHasT]

Hello! I have a problem with my PC since December 2022.
When I press the power button,fans start spinning but no display. After a few seconds my PC turns off and turns on again by itself.
My motherboard it's a MSI H61M-P25 (B3),pretty old.
I tried everything. Clearing the CMOS,replacing the CPU and the RAM,changing monitor/cable,removing the GPU and tried to boot. Still nothing...
Please,help me fixing this b#llshit.

 

[rgd1101]

full system spec? include brand and model of the psu

 

[qHasT]

Intel i5-3470 3,2ghz Ivy Bridge with Stock Cooler
MSI H61M-P25 (B3)
2x4gb DDR3 Elixir ram 1600mhz
GTX 760 Windforce OC 2gb
High Power PSU HPC-500-G12S 500W
x1 Gigabyte 120gb SSD
x1 Seagate HDD 1TB

I know it's old,but for me it's good for some games and work.

 

[scout_03]

test you psu .

 

[qHasT]

how?