Toughpower not so bad PSU at all. Much better than KCAS or Zalman cheap models. 1200 can handle 6 gpus, but consumption depends on concrete model of gpus, for example, my Gigabyte 5x580s consume 900w from the wall. You need to test your gpus
What algos are this on? Im doing eth/xmr mining at sub 900w for 8xrx580's (Sapphire Nitro)..