ethomaz said:
The size of the buss didn't change the performance of a GPU... the bandwidth change. HD 7770 uses a 128bits @ GDDR5 so only 72GB/s bandwidth... Xbone has a 256bits @ DDR3 so only 68GB/s bandwidth... the Xbone GPU in this scenario (not adding the console optmizations or eSRAM) will have a comparable performace if they run at the same clock but Xbone GPU runs at 200Mhz less clock but have more 2 CUs. But we are talking ot about CUs or core speed here. In terms of bandwidth it is really low for a GPU of 7770 power... in fact HD 7770 was a disapointed when launched due the 128bits bus... the 256bits with GDDR5 should be a killing GPU. 72GB/s bandwidth make the HD 7770 be weaker than GPU launched two year before with more bandwidth like:
Just for reference the specs of the GPUs listed. HD 5870: GDDR5@256bits 153GB/s Of course... the HD 5870 have better specs but the GTX 560 not... there are the GTX 570 and GTX 580 over the GTX 560. |
All this is fine and correct when it comes to PC GPUs but not how things are set up to work on Xbox One.
The Xbox One will have 68GB/sec of bandwidth between the CPU/GPU and RAM. Also the GPU will have 102GB/s of bandwidth to a local 32MB SRAM cache, and another 30GB/s of bandwidth to gamepads, Kinect, and other peripherals.
Even PS4 isn't as simple since on the PS4 side, you have 176 GB/s between CPU/GPU and everythign else. 7850/7870 have around 150 GB/s if I remember correctly, but that is only for the GPU. PS4 has to share that bandwidth between everything.
Here is an example of how Xbox 1 will work at maximum load (1080p@60 fps) - http://www.vgleaks.com/durango-memory-system-example/
There is way more shit going on here that... RAM speed + Bandwidth + GPU cores
