I dont recommend the 192's... I am only getting from 5k- 6300. I have a couple that are @ 8k but I dont know if those #'s are accurate. I think The 216 260's should get in the 7 k range

I fint it like this: 9800gt= 4500k give or take...gts 250 is approx 1k more ppd, 260 216 is approx 1k more ppd more than 250, gtx 275 is approx 1 k more than 260, and would guess the 285 would be approx 1 k more than 275. I would say give or take approx 500 ppd for ea. my gtx 275 gets into the 92-9300k range so that would be approx 1500 ish more than 260.

This is roughly what I have concluded in my research. Obviously depends on wu's. Me personally I would run at least a gtx 260 216 if your trying to push out more ppd. JMO though

EDIT:lol, or are you trying to compare your gts 250's? shouldnt be too far behind the 260s, still approx 1k