Re: AMD Radeon HD 9970 Hawaii Detailed, Volcanic Islands GPUs Set for Late 2013 (chip hell leak/rumo
The point was not about out doing but keeping up. 680 competes with a paltry 256 bit bus. 7970 does not seem to have an advantage using a wide 384 bit bus.
Wider bus is like a wide highway for better streamlined data feed. Apart from that , you also need an efficient MMU to manage data efficiently through the bus.
The 680's are just a couple of fps lower than the GHz edition. They would still match a standard 7970 with their 256 bit bus. Read up about kepler's memory management unit. They were explained in several early reviews. Its superior to what GCN offers.
Besides, 4k is an overkill resolution for single gpu gaming. Apart from the titan, non of the cards are fast enough. Even titan falters in some.
The point is,it's not that having a wider memory bus with higher bandwidth would benefit you in all situations in gaming but it does benefit in some.Sure different architectures would have different ways of dealing with memory management and though we can talk about if one has a considerably higher memory B/W but that doesn't make it outrightly better in every situation though things change with higher memory uitlisation,resolution,AA.
Wider memory bus and B/W of GPUs of same architecture can be compared better than comparing memory management of two different archtectures as they don't work identically.With kepler nvidia have more cache and higher bandwidth,full 512KB of L2 cache shared through the GPU,the cache hit-rate is optimized than their Fermi chips,SMX units together are more optimized than previous SM units for parallelism.
Even at 1080p hd7970GHz and gtx680 trade blows but at higher resolutions the former is overall better which is quite clear.
At higher resolutions mostly the gap is always in the favor of hd7970GHz.
Far cry 3 is an example,here at 1080p hd7970GHz edition was losing about 20% and tables are turned as soon as we go to 1440p or higher.
So yes higher memory specs definitely help hd7970GHz edition at higher resolutions but how efficiently,is a different question as the question how would gk104 with identical specs to gtx680 with 384bit wide bus,3GB VRAM would fair(definitely better than gtx680 but how much better?) is also a different question.At the end memory bandwidth is just one part of the equation there are other things as well.
And it is not like as if it is just gtx680 is just "couple of fps" lower than hd7970GHz.In many cases it is just much more substantial than that at 1440p or higher,sometimes like 15-20% and sometimes even more than that(dirt3,skyrim,sleeping dogs).Gtx680 can't
keep up with hd7970GHz edition here at higher resolutions.
For sure at 1440p,4k and higher resolutions most would prefer a mutli-GPU set up but that doesn't change the thing that hd7970GHz is better at 1440p or higher,a step ahead of gtx680.