Well actualy i was using the same PSU at my first build which i bought in 2010-12 and it worked well until 2011-06 when i accidentaly spit some water on the psu so it broke up however it didnt mess up any of the other components. I was glad because of that so i bought new same psu few days later. So im using another same chieftec psu since 2011-08 till now and didnt have problems. If i bought new psu and then i would lack money for my gpu.
There was suggestion for 270x, but it uses more power than 270, i think ill go for r9 270 since benchmarks doesnt show a lot of a difference between these two