David:
I did a bunch of checking, and, most of the reviews find the 1600 half the speed of the 1900, and, about the same half speed of the XL 800-850, which are half the price. WHY????
Also, since you DO tend to overclock, WHY are you going with a passive cooling solution? I just got my 800 back from Gigabyte, but, I'm NOT doing another passive cooling solution, because I tend to sit for 8 hours playing games, the same, your gaming machines do.
The top end Nvidia DOES KICK BUTT, and, in your favorite mobo, should be able to do the two cards, one out, sli stuff. Very cool for Quake 4...;-)
Greg