Frequency Analysis: Cutting Back on AVX2 vs Kaby Lake

Analyzing a new CPU family as a mobile chip is relatively difficult. Here we have a platform that is very much hamstrung by its thermal settings and limitations. Not only that, the BIOS adjustments available for mobile platforms are woeful in comparison to what we can test on desktop. This applies to the Intel NUC that came to retail in December as well as the Lenovo Ideapad E330-15ICN that we have for testing.

The issue is that for a 15W processor, even when built in a ’35 W’ capable environment, might still hit thermal limits depending on the configuration. We’ve covered why Intel’s TDP often bares little relation to power consumption, and it comes down to the different power levels that a system defines. It can also depend a lot on how the chip performs – most processors have a range of valid voltage/power curves which are suitable for that level of performance, and users could by chance either get a really good chip that stays cool, or a bad chip that rides the thermal limits. Ideally we would have all comparison chips in a desktop-like environment, such as when we tested the ‘Customer Reference Board’ version of Broadwell, which came in a desktop-like design. Instead, we have to attach as big of a cooling system as we can, along with extra fans, just in case. Otherwise potential variations can affect performance.

For our testing, we chose Intel’s Core i3-8130U mobile processor as the nearest competition. This is a Kaby Lake dual core processor, which despite the higher number in its name is using the older 14nm process and older Kaby Lake microarchitecture. This processor is a 15W part, like our Cannon Lake Core i3-8121U, with the same base frequency, but with a slightly higher turbo frequency. Ultimately this means that this older 14nm processor, on paper, should be more efficient than Intel’s latest 10nm process. Add on to this, the Core i3-8130U has active integrated graphics, while the Cannon Lake CPU does not.

Because both CPUs have turbo modes, it’s important to characterize the frequencies during testing. Here are the specifications and turbo tables for each processor:

Comparing Cannon Lake to Kaby Lake
10m Cannon Lake
Core i3-8121U
AnandTech 14nm Kaby Lake
Core i3-8130U
2 / 4 Cores / Threads 2 / 4
15 W Rated TDP 15 W
2.2 GHz Base Frequency 2.2 GHz
3.2 GHz Single Core Turbo 3.4 GHz
3.1 GHz Dual Core Turbo 3.4 GHz
2.2 GHz AVX2 Frequency 2.8 GHz
1.8 GHz AVX512 Frequency -

The Cannon Lake processor loses frequency as the cores are loaded, and severely loses frequency when AVX2/AVX512 is applied based on our testing. Comparing that to the Kaby Lake on Intel’s mature 14nm node, it keeps its turbo and only loses a few hundred MHz with AVX2. This part does not have AVX512, which is a one up for the Cannon Lake.

The biggest discrepancy we observed for AVX2 was in our POV-Ray test.

Here the Kaby Lake processor sustains a much higher AVX2 frequency, and completes the test quicker for a 26% better performance. This doesn’t affect every test as we’ll see in the next few pages, and for AVX-512 capable tests, the Cannon Lake goes above and beyond, despite the low AVX-512 frequency. For example, at 2.2 GHz, the Kaby Lake chip scores 615 in our 3DPM test in AVX2 mode, whereas the Cannon Lake chip scores 3846 in AVX512 mode, over 6x higher.

The system we are using for the Core i3-8130 is ASUS’ PN60 Mini-PC. This device is an ultra-compact mini-PC that measures 11.5mm square and under 5cm tall. It is just big enough for me to install our standard Crucial MX200 1TB SSD and 2x4GB of G.Skill DDR4-2400 SO-DIMMs.

For the Cannon Lake based Lenovo Ideapad 330-15ICN, we removed the low-end SSD and HDD that was shipped with the design and put in our own Crucial MX200 1TB and 2x4 GB DDR4 SO-DIMMs for testing. Unfortunately we can’t probe the exact frequency the memory seems to be running at, nor the sub-timings, because of the nature of the system. However the default SPD of the modules is DDR4-2400 17-17-17.

Intel’s Core i3-8121U: Uncovering the Microarchitecture Secrets Our Testing Suite for 2018 and 2019


View All Comments

  • BigMamaInHouse - Friday, January 25, 2019 - link

    Thank you for your Great reviews.
    Look like we should not ecpect much from those new 10nm CPU's for cunsumers for new future, maybe in Q1 2020 with 10++ gen.
    2019 going to be on AMD's Favor!.
  • jaju123 - Friday, January 25, 2019 - link

    12 or 16 core Ryzen with a 13% IPC increase, at equivalent power to the i9-9900k is not going to go well for Intel. Seems like they'll be able to compete with the AMD processors of 2019 around late 2020 at the earliest. Reply
  • ZolaIII - Friday, January 25, 2019 - link

    Take a look at the Spec 2006 benchmark and make the comparation to A76 (Snapdragon 855) it beats this Intel SKU (@2.2 GHz) In most cases with only half the power used. When SVE NEON SIMD lies in CISC is doomed. Reply
  • Gondalf - Friday, January 25, 2019 - link

    Unfortunately we don't know how perform AMD new cpus, only cherry picked results nothing more.
    Even less we know about power consumption. Are we certain AMD 7nm cores will are winner over 12nm ones?? AMD is unhappy about clock speed for example, so the IPC advantage will be likely vanished.
    IMO AMD is painting a too bright future to be trusted. TSMC process is not perfect at all, instead of Nvidia should be on it right now.
  • levizx - Saturday, January 26, 2019 - link

    Rubbish written in garbled words. Reply
  • KOneJ - Sunday, January 27, 2019 - link

    What exactly are you trying to babble about here? Reply
  • Valantar - Sunday, January 27, 2019 - link

    Lying about future products is grounds for lawsuits from shareholders (and possible criminal charges many places), so that's quite unlikely. We do have one indication of power draw from Zen2, from the live Cinebench demo where an 8-core Zen2 chip matched the 9900K's score at ~50W lower power. Of course we don't know how clocks will scale, nor the clock speed that test was run at, and it's relatively well established that Cinebench is a workload where AMD does well. Still, TSMC 7nm is proven good at this point, with several shipping large-scale SKUs on it (Apple A12, A12X, among others). Even if these are all mobile low-power chips, they're very high performance _and_ low power, which ought to fit Zen2 well. Also, the Cinebench score matching the 9900K means that either IPC has improved massively, SMT scaling on Zen2 is ~100%, or clocks are quite high. Likely it's a mix of all three, but they wouldn't reach that score without pretty decent clocks. Reply
  • Samus - Thursday, January 31, 2019 - link

    Ignoring any Zen IPC improvement whatsoever, process improvements alone this year would make them competitive with Intel going forward. All they need to do is ramp up the clock frequency a bit without a TDP penalty and they have an automatic win... Reply
  • Makste - Saturday, March 6, 2021 - link

    Lol😆 Reply
  • Vegajf - Friday, January 25, 2019 - link

    Icelake desktop will be out 3q 2020 from what I hear. We will have another 14nm refresh before then though. Reply

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