Help computer won't start

[paulenworb]

i was building my custom pc and when i finished it wouldn't start and i don't know why. I've tested the power supply and it works. i've scraped it back down so that at the moment i only have the power supply plugged into the mother board

[Villanity]

Are you sure your cables are fine? Is it brand new or old? 

[paulenworb]

new i tested the cables with a paper clip aswell

 

[paddy-stone]

Spec?

[Sovek]

is your switch on the correct pins on the motherboard? is the power switch on the back of the PSU on.  Oh, and make sure your EPS wires are plugged in. 

[paulenworb]

yes there all pluged in is there a 

9 minutes ago, Sovek said:

is your switch on the correct pins on the motherboard? is the power switch on the back of the PSU on.  Oh, and make sure your EPS wires are plugged in. 

yes there all pluged in, could there be a problem with the motherboard ?

 

[paulenworb]

12 minutes ago, paddy-stone said:

Spec?

corsair 650 watt b450m pro 4 motherboard