There's the Sapphire 7970 for $450 (I realize you said reference, but why would you limit it to reference only? It makes no sense.).
Stop with all the drama.
I had my eye on the Sapphire for a while but that card is getting a mixed bag of reviews and even professional reviewers have noted that it has coil wine. That's a deal breaker imo. If it didn't have coil whine in so many reviews/user feedback, I'd consider recommending it.
The reason I mentioned reference 7970s is because I still can't believe they are going for $450-490. In light of the 670 Top card, those cards no longer make any sense. GTX670 Top = 680 in performance and costs $450, has premium components and one of the quietest fans....that's like having GTX680 performance with a quiet cooler for $450. Reference 7970s basically need to drop to $399 now to make any sense at all.
The biggest problem for AMD is that at stock speed for 1080P,
GTX670 = HD7970 and GTX670 OC = GTX680 which means it's faster out of the box than the 7970. It's very difficult to sell a slower product for higher prices just because it overclocks better. That strategy has never worked. All great overclocking products became legendary because they sold for reasonable prices and could overclock well (Thunderbird XP1700+, Barton XP2500+, Q6600, 6800GT, 8800GT, 5850). HD7970 costs more than GTX670 but it needs to be overclocked to beat it. That's not leading price/performance, especially not when 670 beats it in modern games like BF3, SKYRIM, etc.
Until AMD drops prices, GTX670 will continue to cement its status as the 6800GT of this generation.