430W

5770 being the best, yes. 1x 6-pin.

HD 5770.

yes, i know it is good, apart from the grey screen issues. However, I was wondering how much wattage each would suck up.

Yeah, it should be ok. That's enough power, but I'd recommend a little more if you do heavy gaming.

http://www.techpowerup.com/reviews/HIS/HD_5770/28.html

5770 is 25 Watts lower power consumption than 9800GT.
3850 is 23 Watts lower power than 9800GT.

I don't know where you got those numbers from but they aren't right. The HD5770 uses about 10w less under load and the HD3870 5w. And that is only in comparison to the older 9800GT with the power connector. The newer version uses significantly less power than either of them.

does the new version perform as well as the old version?

The new version of the 9800GT is slightly underclocked, from 600 to 550mhz. It can easily be put back up to the normal speeds by OCing however.

Best answer selected by pleasenoname.