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Memory Scaling, AMD's Trinity APUs, And Game Performance

Power, Average Performance, And Efficiency

Our motherboard automatically ramped up voltage whenever we changed the memory ratio to run at DDR3-2400 data rates. Those changes, which we didn't ask for, but are imposed (and maybe even necessary for stability) anyway are reflected in a big power consumption jump compared to running at DDR3-2133. The only way to get normal readings at 2,400 MT/s would have been to use modules rated for that data rate, and not overclocked to get there.

Interestingly, GPU power increases about 1 W for every step up in memory data rate (excluding the DDR3-2400 result, which is abnormal and due to the motherboard’s automatic voltage increases). For this combination of motherboard and memory, the easiest way to have your performance and efficiency is to leave it at XMP values.

DDR3-2400 only yields 2% more performance than DDR3-2133, while DDR3-2133 generates a huge 20% gain over mainstream DDR3-1600.

If all else were equal, we’d expect the performance lead attributable to DDR3-2400 data rates to show up in an efficiency chart. Because Asus' board juices voltage to enhance stability, though, we don't get the efficiency pop we were expecting.

Even still, the 20.4% speed-up from DDR3-2133 is far larger than the power consumption premium imposed by G.Skill's kit. So, that faster memory setting does deliver higher efficiency.

  • hmp_goose
    Neat stuff, but how sensitive is an IGP to timings?
    Reply
  • Wisecracker
    Thanks.

    The question is ... does the performance with higher speed memory continue to scale as the *SIMD Engine Array* is over-clocked.

    Inquiring minds would like to know ...

    Reply
  • Onus
    And there were a few games where the faster memory was required simply to break us into our minimally-accepted 40 FPS average.
    Right there. An APU is not a top-tier gamer, so incremental improvement really matters. I could not care less about going from 60FPS to 80FPS, but 30FPS to 40FPS, the same relative improvement, is a really big deal.
    Reply
  • esrever
    Can't wait to see what DDR4 can do for APUs.
    Reply
  • slomo4sho
    I would really like to see some 5760x1080 benchmarks.
    Reply
  • slomo4sho
    slomo4shoI would really like to see some 5760x1080 benchmarks.
    Individuals who would use faster memory for gaming are likely to want to push their mid/high range card to the limits, do you plan on doing a similar piece for AMD CPUs as you did in the Intel article "Does Memory Performance Bottleneck Your Games?"

    Also, I would like to see a Nvidia card at play as well. Maybe a 650 Ti or 660 Ti? In addition, it wold be nice to see the memory scaling difference between AMD and Nvidia GPUs in a single review.

    Thanks.
    Reply
  • merikafyeah
    esreverCan't wait to see what DDR4 can do for APUs.Considering how DDR3-2400 is only a tiny fraction better than DDR3-2133, it's safe to assume memory stops being the bottleneck around that point. DDR4 will not noticeably improve performance or even power consumption as memory consumes almost negligible amounts of electricity to begin with.

    It's back to looking at better GPUs and CPUs for better performance.
    Bpttleneck hierarchy has always been GPU>CPU>RAM.
    The CPU has always been more reliant on the RAM than the GPU but an APU is basically a GPU+CPU in one, so RAM is more important, but as we've seen, only up to DDR3-2133. After that diminishing returns skyrocket.
    Reply
  • jubas
    slomo4shoAlso, I would like to see a Nvidia card at play as well. Maybe a 650 Ti or 660 Ti? In addition, it wold be nice to see the memory scaling difference between AMD and Nvidia GPUs in a single review.I didn't know that nVidia made APU's?
    The more you know... /rollseyes/
    Reply
  • de5_Roy
    quite promising performance from trinity.
    still, 15 gb/s out of ddr3 2400 ram is just sad. i expect amd to improve in the next gen apus. the igpus deserve the extra memory bandwidth.
    i wonder how cpu overclocking (along with igpu and ram oc) affect the games like skyrim, starcraft and f1. those seemed more memory sensitive.
    Reply
  • austenwhd
    When will they integrate a gpu to FX module, that will be blast.
    Reply