May 31, 2011
Currently, the onyl advantage of gaming consoles is huge cpu-gpu interconnect bandwidth:
PS3: Cell FlexIO bus interface
20 GB/s read to the Cell and XDR memory
15 GB/s write to the Cell and XDR memory
XBOX360: 21.6 GB/s front side bus
10.8 GB/s upstream and downstream
it looks huge (especially ps3) in comparision with pci-express 2.0 x16
which is 8GB/s upstream and 8GB/s downstream. It isn’t bottleneck in current game’s developing paradigm because it was created to workaround that bottleneck in ages of pci-e 1.1 or even agp. Just compare 2gb of vram on 6970 and 256mb vram on ps3. Cell cpu in ps3 can quickly feed gpu with needed data without the need to store everything in vram to keep up with fps. On pc, for sake of speed you gonna store as much as possible in gpu’s vram. (Yeah, I understand the difference in the output resolution, but still..)
But, next generation of pc gonna fix that, there is already a lot of pci-e 3.0 mainboards you can see on computex these days. Its gonna be released when sandybridge-E and ivybridge will be launched.
Pci-e 3.0 gonna give us 16 GB/s downstream and 16 GB/s upstream, which is now comparable to ps3.
I just wonder what game developers can do if they will not care about backward compatibility and will fully use that 32 GB/s (total bandwidth) line.