i used to have this problem with a gigabyte GTX280, simply "forcing" vsync ON in cp fixed the whining which used to happend at anything above 100+fps, the higher the fps the higher the frequency of the shriek (ear piercing at times).
clock to clock it is .... the point was not to say a slower 670 will be 2-4% under the 680, it is more in the 7-10% ... hence why i have take the article of TH who use an EVGA 670 who is at least with close clock speed of the 680. Now this is what have been seen with 1SMX lost, maybe 2 and less TMU, ROP will bring a different impact.
When the GTX 260 was released, a $400.00 cards was not considered a midrange card. Even today a $400.00 card is not considered midrange.
The EVGA 670 SC has a boost clock 12 MHz less than the reference 680. Now lets look at a 670 with a boost clock 21 MHz higher than a reference GTX 680. http://www.guru3d.com/article/msi-geforce-gtx-670-power-edition-oc-review/17
MSI 660 'Thunder' - Dual Bios /1120 Cores @1066MHz, 6.5Ghz DDr5 3 - 4GB Vram. £399 The gpu has a nice devil red backplate. : )
Depends on what version they eventually release. GTX 680 is still quite expensive as its almost 4000Dkk/$690 pr card. If I can get 3 GTX660Ti for less the price of two GTX 680 and they'll match the performance or even surpass buy 10-15% I'd take them...if 3-way SLi is possible.
I got a GTX260 core 216 when it came out and it was $289.99. The first 260 was 18% behind the 280 I would not call that any thing remotely like the 670/680 comparison. I will say both the 280 @ $650 and the 260 @ $400 where way over priced.