can i add a GPU with OCZ ZT Series 650W 80+ Bronze Modular
Its not the best PSU in terms of quality. Just because it says 650w doesn't mean it will actually make 650w. Yes you could add a GPU no problem, however the PSU is more likely to fail and ruin components than one of a more reputable brand.
what about Antec NeoECO 620C Bronze this is any good?
Yes it is.
im going with Antec High Current Gamer 620W Power but NeoEco and hight current gamer any diff??