Ok so i made a thread asking if i could sli 970s on a evga supernova 750b psu. My microcenter said it was a great psu (back when i knew nothing about computer hardware). So i know that i can sli with headroom and this unit has not given me any issues but i know its reviews are not very good and its near the bottom of toms tier list. I have had this unit for about a year. Should i upgrade to something on the top tier list? it makes me nervous....