Mark Roulo (nothanks.delete@this.xxx.com) on April 23, 2013 3:20 pm wrote:
> You have capacity limitations and memory bottlenecks at several places. So ...
>
> The Intel IGPU has a bandwidth advantage going to system DRAM because it shares the memory controller (and
> access to the system DRAM) with the CPU. The discrete part is bandwidth limited because of PCIe.
>
> I get how more memory (1 GB vs 128 MB) at fast speeds (64 GB/sec +) is good, but I'd also think that access
> to the rest of the system memory at faster speeds (25 GB/sec vs 5-10 GB/sec) would be good too.
>
> Any idea how these two factors compete? I don't game and have no idea ...

All present-day games have been designed and programmed with the latency and bandwidth of the PCIe link in mind. I personally believe that bringing the GPU closer to the CPU will be a major win that will help much more than just raw power, but that is only *after* games can rely that they are indeed close. Right now, the PCIe link is just a common design constraint, meaning that bringing the GPU and CPU closer together buys you *nothing* on present games.

PS4/the next XBOX should help with this, as they are APU designs that will teach game programmers how to exploit such architectures. For the shelf life of Haswell, I don't believe that a single game will exist that takes proper advantage of this.