After many months of waiting, Amazon today has finally made available their new compute-oriented C5a AWS cloud instances based on the new AMD EPYC 2nd generation Rome processors with new Zen2 cores.

Amazon had announced way back in November their intentions to adopt AMD’s newest silicon designs. The new C5a instances scale up to 96 vCPUs (48 physical cores with SMT), and were advertised to clock up to 3.3GHz.

The instance offerings scale from 2 vCPUs with 4GB of RAM, up to 96 vCPUs, with varying bandwidth to elastic block storage and network bandwidth throughput.

The actual CPU being used here is an AMD EPYC 7R32, a custom SKU that’s seemingly only available to Amazon / cloud providers. Due to the nature of cloud instances, we actually don’t know exactly the core count of the piece and whether this is a 64 or 48- core chip.

We quickly fired up an instance to check the CPU topology, and we’re seeing that the chip has two quadrants populated with the full 2 CCDs with four CCXs in total per quadrant, and two quadrants with seemingly only a single CCD populated, with only two CCXs per quadrant.

I quickly ran some tests, and the CPUs are idling at 1800MHz and boost up to 3300MHz maximum. All-core frequencies (96 threads) can be achieved at up to 3300MHz, but will throttle down to 3200MHz after a few minutes. Compute heavy workloads such as 456.hmmer will run at around 3100MHz all-core.

While it is certainly possible that this is a 64-core chip, Amazon’s offering of 96 vCPU metal instances point out against that. On the other hand, the 96 vCPU’s configuration of 192GB wouldn’t immediately match up with the memory channel count of the Rome chip unless the two lesser chip quadrants also each had one memory controller disabled. Either that, or there’s simply two further CCDs that aren’t can’t be allocated – makes sense for the virtualised instances but would be weird for the metal instance offering.

The new C5a Rome-based instances are available now in eight sizes in the US East (N. Virginia), US East (Ohio), US West (Oregon), Europe (Ireland), Europe (Frankfurt), Asia Pacific (Sydney), and Asia Pacific (Singapore) regions.

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  • ads295 - Friday, June 5, 2020 - link

    Reading articles like these reminds me how little I know about server workloads and the custom chips that are the result of that. I understood nothing about this article!
  • ingwe - Friday, June 5, 2020 - link

    You aren't alone! I feel the same way about server articles on AT.
  • imaheadcase - Friday, June 5, 2020 - link

    Because when anand left the current person in charge is more interested in technical hardware stuff now than actual stuff a regular person would use at home. Sure they throw up some news/reviews of other hardware..but no way as popular as when it was geared towards more basic hardware.
  • brantron - Friday, June 5, 2020 - link

    Hi, former regular person here, and I've been using cloud instances at home for 5 years. I guess all the bazillion people who were able to switch to working from home at the push of a button aren't regular anymore, either. The world has suddenly become a lonely place for the few remaining regular people...
  • aryonoco - Friday, June 5, 2020 - link

    Speak for yourself. I find the server articles, the HPC and the mobile articles far more interesting than yet another PSU or case review. The PC market is boring, servers and mobile is where all the innovation is happening.
  • Foeketijn - Sunday, June 7, 2020 - link

    I'm pushing that imaginary +1/thumbs up/heart button.
  • jospoortvliet - Sunday, June 7, 2020 - link

    same here, I've seen enough power supplies. The technical deep dives in cpu, gpu and other components are what make this site stand out from the gazillion others.
  • voicequal - Wednesday, June 10, 2020 - link

    Anandtech continues to deliver content and analysis you'd be hard pressed to find anywhere else. PC, mobile, server, cloud, etc are all underpinned by much of the same foundational tech, and technologists will see how an advancement in one space has future implications for another. I suspect more tech sites than you realize (still) get inspiration from Anandtech.
  • ads295 - Friday, June 12, 2020 - link

    To be sure, I'm not complaining, the purpose of any information is to broaden one's mind. I had no idea about lithography processes, DVFS curves, DeltaE readings and the like 10 years ago, when I was still learning about dual channel memory and getting kicks from increased CD read speeds by changing every PC's drive I could lay my hands on, from PIO to DMA mode. Maybe someday server hardware and workloads will make sense to me too.
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