That's cool. I never said you had to strip down your PC to change the GPU.
http://gpu.userbenchmark.com/Compare...6GB/3609vs3639 £150 difference between the 1060-1070
https://uk.pcpartpicker.com/product/...ly-100b10500kr £50 for 500W
https://uk.pcpartpicker.com/product/...ly-100b10600kr £62 for 600W
So yeah it is much cheaper to get a better PSU now and leave your options open for the future.