Motherboard not working.... or something else?

My cuz is a techy, been building pc's processionally for 6 years, friend of mine at work as recreationally built them for over a decade and we are all stuck on this 1 pc ive chosen.

Ill say the rest of the spec too but I have even tried this with just the mobo, cpu, psu and 1 stick of ram in socket a1 and it doesnt work.
I have replaced a faulty motherboard, went from Asus to Asrock and doesnt work
returned the cpu in case it was faulty, retails hasnt confirmed that yet, thinking it might not have been
used 3 different psu's both of the other 2 were from working machines
tried all 4 sticks of my ram in slot 1 as well as ram from a working machine
cuz who does this for a living checked/ done all the tests again and reset bios

all of these changes have the exact same effect, pc comes on for 1 second and switches off again, the led on the mobo reads number its checked to and always gets to 19, which looking at the manual would suggest ramm checks have been done but its not done the cpu check (might be wrong there but that was my take)

only suggestion is that it might be cpu or mobo however checking every single pin with a microscope cant see anything wrong, 1 pin is slightly shiner not really material but we spent an hour checking it to make sure is wasnt bent or broken as we couldnt for the life of us think what to check next


Specs are

Asrock x79 extreme 9 (2011 socket)
i7 3820
Corsair vengeance ddr3 4x4gb 1866Mhz
Corsair 850W HX 80PLUS Gold Modular PSU

Corsair H100 water cooler
Asus HD 7770 2GB AMD Radeon Graphics Card

OCZ 120GB Solid 3 SSD


then got the other Harddrives, bluray drives and so on but not even got to that so no point going into the rest


Any idea what so ever to what I can try, dont want to return mobo and cpu again if these ones are ok, when it switches off you can hear a click on the powersupply almost like its activated the failsafe to stop it frying something but I might just be making things up in my head to justify its defiance!

Thanks all