I would suggest not going with GTX 650. It's severely underpowered and overpriced. Go with GTX 650 Ti instead; it's just a bit more expensive but much more powerful.
By alimentator I suppose your mean the power supply unit
? If you buy a new one, make sure to stick with one of the quality brands, that is Antec, Corsair, FSP, Seasonic and XFX. Stay away away from brands like Cooler Master, their power supply units aren't worth a penny.