And psu can now handle the load.
as a rule of thumb 60% on an atx works well 24/7/365. and 1300 x .60 = 680 watts.
Just realized that 1300 x.6 is 780 watts
Anyway, I kept changing the voltage down to 875mV for both core and memory and it is still stable.
How much is it safe to downvolt?, I don't dare to put any lower value.