That's usually an OC error additionally you may have a bad riser. Try downclocking all cards. I found my 1060 3GBs run at 400-600 memory(depending on brand) and +100 core. The Best way to test a riser is to put as much power as the cards can handle, mine a GPU intenstive coin like Zcash and see how long it takes before it crashes.

Method you wanna take for this is,

Plug 1 card in, run the miner, max power no OC. Run for at least one hour.
Plug 2nd card in, etc
and so on until you find one that fails, swap the riser. If they all pass then start OCing all of them. First try your settings then if they fail there back off until they no longer crash.

Mind you this is time intensive. Problem solving always is when you have an unknown "Watchdog" error like that.