Can gtx 750ti or gtx 1050ti or gtx 1050 support i3 540? And if support which is a good combination of i3 540? My motherboard is intel corporation dh55pj.
Supporting GPU depends from motherboard not CPU. I would personally buy new CPU (used one it should be cheap) like X3430 If of course your motherboard supports it, which is your motherboard?(and overclock it a bit)
And which games are you looking to play?