PC turns on but no signal to monitor or usb

[daniel.g17]

so i have a old pc that has a core i7 with a MSI H67MA-E35 (b3) motherboard and 2x4gb elixir DDR3, a antec 750w PSU and a sandisk 250bg ssd plus which I bought recently and it work at the start but my pc recently just stopped working and would turn on but have no signal to the monitor and the usb ports didn't work (plugged in keyboard and tried to see if the led capslock symbol would light up but didn't, this might just happen when pc are starting up though) when I turn it on the CPU fan spins and the card reader mounted on frount leds light up but that's it. I also unplugged my gpu and used on board graphics but same still.

I tryed another motherboard,cpu and ram that has a core i5 with an asrock H61M-HVS motherboard with 2x4gb of arams DDR3but the same problem was still there.i also unplugged the gpu and used the onboard but nothing changed

I also recently bought a Geforce GT 710 to test but that still had no effect.
the PSU is only about a year old and never had problems with it.

PLZZZZ help...

 

[Tolis_GR]

Well with so many different configurations, it looks like a psu problem.