I can't believe the new Nvidia GTX 980 has only 2048 Cuda Cores with lower specs than the GTX 780 Ti and according to benchmarks online, it manages to trade blows with the GTX 780 Ti - I guess the performance is due to the incredibly higher clocks on both the core and memory. I still have my doubts though about the performance. Remember the GTX 680? It defeated the 7970 back in earlier 2012 after its release with lower specifications than the 7970. I know they have different designs on how they work, but look what happened now? The GTX 680 which is now the rebadged GTX 770 is slightly slower than the 7970 ghz which is basically a rebadged R9 280x. I guess that's what happened as GPU drivers mature. I don't know what to expect with the GTX 980, but I'm very impressed of what Nvidia has done to it, especially the power efficiency - marvelous. I just hope it continues to be better or in par with GTX 780 Ti and doesn't end up as what the GTX 680 has become - now slightly slower than the 7970 (R9 280x) - unlike before it was released.
You cant compare core to core with different architectures, also looking at the die sizes these cores are bigger, contain more transistors, and they operate at higher frequencies, so it isnt as big an advantage as it may seem. Interestingly the R9 290 and 970 have similar die size. But they perform better for their die size when comparing the 980 and 880ti for instance.