Build a PC Gigabyte G1Assassin 2 Motherboard/Corsair AX 860i won't power up

Alex Thomson

TS Rookie
I have put together a new build with the Gigabyte Assassin 2 m/board and a Corsair AX 860i PSU. On start up the PSU clicks out and won't run. The PSU Self test is good - green light and the fan is running, however when I connect all the peripherals the PSU just drops out and will not run. I have double checked all connections from the CPU, M/board, memory, graphics cards. This is all in a Thermaltake Level 10 case, my next check will be the hard drive connections - hot swap bays. Any help will be really appreciated.