Yeah, that's what confused me, that "PLUS" on the name, because I always thought it was a 680i. I scrambled over to newegg real quick when Hex posted after me and saw the P5N32-E SLI, didn't see the "plus" after it and it said 650i so I thought "okay, guess I was wrong."
Should've stuck by my original statement.
And what the heck? "Plus" usually means better, doesn't it? But in this case it means an inferior chipset? Yah, that makes sense.
So I think a 1/1 ratio would do you good after all. I'd try it if you're having problems out of your OC.