Image: Intel

One of the more exciting aspects of Intel’s upcoming 12th Gen Core “Alder Lake-S” processors is their support for DDR5 memory, which promises a significant boost in bandwidth and data rate versus its predecessor. New benchmarks spotted by hardware leaker harukaze5719 provide some insight as to what this exciting combination might bring for enthusiasts who decide to upgrade to blue team’s latest and greatest.

The benchmark stems from a system leveraging a 12th Gen Intel Core i5-12600K (10C/16T) processor clocked at 4.59 GHz with DDR5 memory running at 6,400 MHz. The memory is shown with a read speed of around 90 GB/s, write speed of around 88 GB/s, and copy speed of around 77 GB/s. These bandwidth figures are pretty impressive, but the latency seems worrisome at 92.5 ns.

In the last decade, Intel hasn’t released a single architecture that approached 92.5 ns of memory latency. Only AMD’s original Zen architecture was capable of such laggy behavior, and it was known for its memory bottlenecks in that first-generation iteration.

The reason for this increased latency seems to relate to Intel’s new Gear 4 mode, which the DDR5 memory in this test is reportedly running at. Gear 1 and Gear 2 models were introduced as part of the Rocket Lake generation to improve memory support, with the former running the memory controller and RAM at the same frequency for lower system latency and the latter reducing the memory clock to a 2:1 ratio in order to reach higher frequencies and bandwidth.

Intel’s new Gear 4 mode goes even further by reducing the memory controller frequency to a quarter of the memory frequency, which, while improving support for faster memory, evidently increases latency by quite a bit.

Source: harukaze5719 (via Tom’s Hardware)

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3 Comments

  1. Yes, I have heard that in this first generation of DDR5 latencies are going to be bad. So bad, that very fast DDR4 could beat out the lower-end of DDR5 in this first generation, it’s just the nature of evolving hardware. As the process matures, DDR5 ultimately has greater potential, but first, we have to go a little backwards before we can move forwards. DDR5, in time, will have very low latencies, but it may take a couple of generations.

    If latency is important in your workload, you may want to stick with DDR4, but if bandwidth benefits your workload, DDR5 will benefit.

  2. [QUOTE=”Brent_Justice, post: 41268, member: 3″]
    Yes, I have heard that in this first generation of DDR5 latencies are going to be bad. So bad, that very fast DDR4 could beat out the lower-end of DDR5 in this first generation, it’s just the nature of evolving hardware. As the process matures, DDR5 ultimately has greater potential, but first, we have to go a little backwards before we can move forwards. DDR5, in time, will have very low latencies, but it may take a couple of generations.

    If latency is important in your workload, you may want to stick with DDR4, but if bandwidth benefits your workload, DDR5 will benefit.
    [/QUOTE]
    I believe the same happened with ddr2 -> dd3r and ddr 3-> ddr4? They will get it nailed now in a year or so.

  3. [QUOTE=”Endgame, post: 41273, member: 1041″]
    I believe the same happened with ddr2 -> dd3r and ddr 3-> ddr4? They will get it nailed now in a year or so.
    [/QUOTE]
    Yup; I think everything up to DDR2 performance didn’t backslide, but up to that point the performance (additional bandwidth) was needed.

    [QUOTE=”Brent_Justice, post: 41268, member: 3″]
    If latency is important in your workload, you may want to stick with DDR4, but if bandwidth benefits your workload, DDR5 will benefit.
    [/QUOTE]
    This is really key: latency, as measured between the request for and return of the smallest unit of addressable data, will increase with DDR5. Bandwidth going up significantly will compensate for this a bit. However, there’s a transfer size where latency is the same, and everything larger than that will be faster on the higher-bandwidth DDR5. As noted the effect will be workload dependent, with DDR5 not likely to bring much benefit to most consumer workloads initially, including gaming.

    And with CPUs being more latency tolerant than not these days, we’re probably not going to see significant real-world performance losses with DDR5 vs DDR4 either. We’re pretty far from Intel’s worst-case scenario of pairing Netburst with Rambus!

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