CPU Tests: Synthetic

Most of the people in our industry have a love/hate relationship when it comes to synthetic tests. On the one hand, they’re often good for quick summaries of performance and are easy to use, but most of the time the tests aren’t related to any real software. Synthetic tests are often very good at burrowing down to a specific set of instructions and maximizing the performance out of those. Due to requests from a number of our readers, we have the following synthetic tests.

Linux OpenSSL Speed: SHA256

One of our readers reached out in early 2020 and stated that he was interested in looking at OpenSSL hashing rates in Linux. Luckily OpenSSL in Linux has a function called ‘speed’ that allows the user to determine how fast the system is for any given hashing algorithm, as well as signing and verifying messages.

OpenSSL offers a lot of algorithms to choose from, and based on a quick Twitter poll, we narrowed it down to the following:

  1. rsa2048 sign and rsa2048 verify
  2. sha256 at 8K block size
  3. md5 at 8K block size

For each of these tests, we run them in single thread and multithreaded mode. All the graphs are in our benchmark database, Bench, and we use the sha256 results in published reviews.

(8-3c) Linux OpenSSL Speed sha256 8K Block (1T)(8-4c) Linux OpenSSL Speed sha256 8K Block (nT)

AMD has had a sha256 accelerator in its processors for many years, whereas Intel only enabled SHA acceleration in Rocket Lake. That's why we see RKL matching TR in 1T mode, but when the cores get fired up, TR and TR Pro streak ahead with the available performance and memory bandwidth. This is all about threads here, and 128 threads really matters.

GeekBench 5: Link

As a common tool for cross-platform testing between mobile, PC, and Mac, GeekBench is an ultimate exercise in synthetic testing across a range of algorithms looking for peak throughput. Tests include encryption, compression, fast Fourier transform, memory operations, n-body physics, matrix operations, histogram manipulation, and HTML parsing.

I’m including this test due to popular demand, although the results do come across as overly synthetic.

(8-1c) Geekbench 5 Single Thread(8-1d) Geekbench 5 Multi-Thread

DRAM Bandwidth

As we're moving from 2 channel memory on Ryzen to 4 channel memory on Threadripper then 8 channel memory on Threadripper Pro, these all have associated theoretical bandwidth maximums but there is a case for testing to see if those maximums can be reached. In this test, we do a simple memory write for peak bandwidth.

For 2-channel DDR4-3200, the theoretical maximum is 51.2 GB/s.
For 4-channel DDR4-3200, the theoretical maximum is 102.4 GB/s.
For 8-channel DDR4-3200, the theoretical maximum is 204.8 GB/s.

(8-2b) AIDA DRAM Write Speed

Here we see all the 4-channel Threadripper processors getting around 83 GB/s, but the Threadripper Pro can only achieve closer to its maximums when there are more cores present. Along with the memory controller bandwidth, AMD has to manage internal infinity fabric bandwidth and power to get the most out of the system. The fact that the 64C/64T achieves better than the 64C/128T might suggest that in 128T there is some congestion.

CPU Tests: Legacy and Web CPU Tests: SPEC
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  • Rocket_Scientist - Friday, July 16, 2021 - link

    I want to know who spends 5 grand on a processor but doesn't spend the few extra dollars to utilize all 8 memory channels!
  • Mikewind Dale - Friday, July 16, 2021 - link

    The 3955WX processor "only" costs $1,150, while each stick of 64 GB RAM costs $350.

    And I wanted to keep some empty slots in case 128 GB RDIMMs became affordable. But I didn't know that using 6 channels would cause so much performance degradation.
  • mode_13h - Saturday, July 17, 2021 - link

    > who spends 5 grand on a processor but doesn't spend
    > the few extra dollars to utilize all 8 memory channels!

    Although I tend to agree, the article did reveal some benchmarks where the additional bandwidth provides negligible benefit.
  • lmh - Tuesday, July 27, 2021 - link

    Can you share what memory bandwidth you actually measured in the 3955WX 8-channel configuration?
  • McFig - Wednesday, July 14, 2021 - link

    There’s an error in the table “AMD 32-Core Zen 2 Comparison”: The MSRPs are mixed up.
  • McFig - Wednesday, July 14, 2021 - link

    Also: “code bath”; “Undreal” (I’m guessing should be “Unreal”?); “but also the updates” (e.g. could be “but also there were significant updates”)
  • SarahKerrigan - Wednesday, July 14, 2021 - link

    I kind of like "Code Bath."
  • Threska - Wednesday, July 14, 2021 - link

    " This is part of AMD’s guaranteed supply chain process, allowing OEMs to hard lock processors into certain vendors for supply chain end-to-end security that is requested by specific customers."

    I ASSUME that's a feature a certain OS vendor can't access.

    "Only select vendors seem to have access/licenses to make WRX80 motherboards, and your main options are:"

    I've seen the Giga offered as a burn-in special with a bundled processor, making it a better deal. The Asus is nice but I have to wonder if it's worth all the features.
  • DesireeTR - Wednesday, July 14, 2021 - link

    No, It's worse. There's article about AMD Platform Secure Boot Feature (PSB) by servethehome together with Dell EMC. It basically burns permanently a public key of the OEM into the EPYC processor. It creates a guarantee that both motherboard and processor are not tampered. If you move your processor from OEM A that enabled PSB to motherboard of OEM B, AMD Secure Processor considers that as tampering and stops it working. The reverse is true.

    Some OEM are very strict (Dell EMC does this by hardware burn-in), some are less strict (HPE use
  • DesireeTR - Wednesday, July 14, 2021 - link

    HPE only locks the public key in the firmware, and perform tamper check on BIOS only). And I guess before long, all PRO processor might get the same PSB feature too.

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