What are your full system specs? A larger PSU isn't a bad thing for future proofing, although the 850w may draw more power from the wall than the 600w version on a system with a lower power draw since the PSU is farther from the peak of its efficiency curve.
Yes, that PSU will work in that case. The case takes ATX PSUs and the EVGA BQ is an ATX psu.
How about the EVGA 650w gold?Yup, the 850w would work with that fine case and provides enough wattage for those specs, although a Seasonic FOCUS would be a better option. The only downside is that the 850w might consume a bit more power from the wall than the 600w. This could be negated by buying an 80+ gold unit.
EVGA 650w GQWhich exact model?
Should fit as well. It is more efficient and should be a better option.