it is always recomended to go for single more powerfull card unless (like me) you got the single most powerfull card on the market and it is not enought. The advantages for SLI is that is more stable and much better then crossfire (had 2 x R9 290X in crossfire and it was a nightmare, now with 2 x gtx 1080 SLI is much much better then cross and pain free). My advice go for a gtx 1060 it is not much over the 1050 and it is a upgrade worth to make.