Cannot enter Bios

[FormulaVI]

Motherboard Asus Maximus VI Formula.
I have just finished my new Build.
I did a test start ( no OS) and I could enter the BIOS all components working everything fine. Since then I have installed a comprehensive Watercooling Loop and add Fans, LED lights, and another SSD
( all checked before installation). Now my PC will
not start. It fires up for about 10 seconds with all fans ,lights and water pump working. then it shuts down, I have double check all my connections( as I thought they may have got dislodged while installing the watercooling components ) .Fans and lighting , water pump are all fine having check them on a external supply. My PSU is a Corsair AX 860i and it was working fine in my first test. Checked again all connections both previous and new to Fans etc.
Can you help?
Obivously 10 seconds is not even long enough to get into the Bios.
Monitor and Keyboard were also working on my first Test ( all my components are new)
PS. I did a Bios flashback USB before my first test and it updated to the most recent, work fine then.

 

[ktriebol]

Remove everything that you mentioned in the first part of your post. Does it work now? If so, add one thing at a time and see if the system works after installing each item.

 

[FormulaVI]

Remove everything that you mentioned in the first part of your post. Does it work now? If so, add one thing at a time and see if the system works after installing each item.

Thats a little difficult as the Processor is now water cooled , so I cannot remove the water pump unless I disconnect the whole Loop, and then the CPU , and the GPU, Motherboard & Chipset have no cooling.The only thing I can check this way would be the fans,and lights. But as I said , I already test these, plus the pump on an external PSU before installing them. However I will disconnect the lights and the fans one by one just to be sure, but I don't think thats going to be the answer, but I will try.
As I said when I switch on all fans and pump are working ( rotating) even if its just a few seconds before the motherboard shuts off.