Originally Posted by Abundant Cores
2048 + 12.5% = 2304 (SP's) would equate to about 5 or 6% in terms of performance, all things being equal. look at the difference between the 1792 SP 7950 and the 2048 SP 7970, its what, 15% more SP's and clock for clock the 7970 is 7%? faster.
What the 50% extra ROP's will do i have no idea, perhaps someone does?
There could be some Shader unit performance improvements.
12.5% more SP on their own are not going to make much difference, the GTX 780 is about 20 to 25% faster at stock than the 7970 GE and about 30 to 35% faster clock for clock.
For the Hawaii XT to trouble the GTX 780 it needs to be 30% faster than the 7970 GE.
It's thought that Tahiti is ROP bottlenecked, hence the small difference between the 7950 and 7970. If that rumor is true and Hawaii only has 12.5% more SPs but 50% more ROPs, it would seem that that bottleneck is rather large, since it would seem that AMD is greatly relying on that for a performance increase. As a rough estimate, I'd say that just the SPs and ROPs make Hawaii up to 20% faster than Tahiti, plus the 5% clock speed increase, and architecture improvements, which themselves could be from 5% to over 20%.
Note that this is speculation based on rumors of unknown accuracy, and thus should be taken with a grain of salt.