Power Consumption - Up to 65W or not?

TDPs and power consumption has been a topic we’ve been revisiting on an (unfortunately) regular basis on almost every product launch. Over the last few generations of product launches in particular, we’ve been attempting to explain the current industry situation in more depth in order to demystify marketed power and thermal envelope figures versus what you can actually expect to encounter in the real products.

Given our limited time in writing up this Tiger Lake-H system, I’ll refer back to our more extensive articles, in particular the in-depth explanation of TDPs and Intel’s new generation product behaviour in our review of the Tiger Lake reference platform last September:

Alongside that piece, we also want to point out more extensive historical talks about TDPs, Turbo and power consumption:

In the context of today’s Tiger Lake-H reference laptop and system, the one thing we must preface the rest of the review is the power settings the laptop came in and the resulting behaviour and thermal characteristics of the Core i9-11980HK SKU we’ll be reviewing today.

Intel’s reference laptop, out of the box as delivered to us by Intel seemingly was set up with no PL1 limit, or at least what we suspect is the maximum cTDP limit of 65W of the i9-11980HK. Generally speaking, this is no surprise as TGL-H is targeting the high-power desktop replacement laptop market which tends to come with capable and extensive thermal dissipation designs.

At first, we started running our tests on the platform in this default reference setting, representing what we had hoped being the best-case scenario for the chip and platform, until we discovered some concerning thermal behaviour when under full load:

Under a Prime95 load in a more prolonged test period of 10+ minutes, when tracking package power consumption as well as CPU temperatures and frequencies, we’re seeing that the TGL-H reference laptop is having great troubles at sustaining this default 65W TDP mode.

During the initial idle period we see the CPU has low power consumption in the 2.2W range with some workload noise in the mix, boosting the CPU frequencies up to 4.9GHz.

The initial load ramp results in peak power consumption of up to 86W, but this is a very transient measurement as power quickly throttles down to 70W and below within seconds. In our readouts it seems that Tau (PL2 turbo period) seems to be set at 5 seconds for this machine.

The worrying behaviour starts happening after around 2 minutes of load: we indeed see the CPU package generally trying to limit itself to around 65W, however it’s not a constant steady state, with very obvious large fluctuations between 65W and 35W.

Looking at the temperature, we’re seeing maximum load figures in excess of 95°C, with some 96°C peaks in our coarse sampled data. What seems to be happening here is that the CPU is thermal tripping between the 65W and 35W states, unable to sustain the 65W state for any amount of prolonged time.

We’ve confirmed that this throttling and power and frequency fluctuations happen on several workloads, and the only conclusion we can come to is that the reference system simply doesn’t have an adequate enough thermal dissipation solution to effectively enable the 65W cTDP mode of the CPU.

While the reference laptop had a bare-bones BIOS, fortunately enough we were able to rely on XTU to change the system’s PL1 settings, and we chose to re-test at 45W given that this is the i9-11980HK’s supposed default TDP setting.

Under this simple change, the thermal, power and frequency response of the system appears to be much more reasonable. We’re still seeing peak power consumption figures of 75-86W which should correspond to the PL2 figures of the chip, but again that’s only for short workloads which fit into the 5 second Tau/Turbo period.

For the remainder of the next 15 minutes, the machine was able to sustain a steady state CPU temperature of around 83°C, and power consumption capped at 45W. Frequencies ended up around 3200MHz all-core for most of the test but had a prolonged 2700MHz period a few minutes in. The 11980HK has an advertised base frequency of 2600MHz, so that seems to be in line with Intel’s specifications.

Unfortunately, we don’t have Intel’s previous generation H-Series processors in house for a direct generational comparison, but the next best thing is the 11980HK’s nearest competitor, AMD’s Ryzen 9 5980HS. This latter chip comes with a 35W TDP which is 10W lower than the new TGL-H SKU we have in house right now, and we see an obvious difference between the chip’s long-term thermals and power, ending up at different levels after some while.

The Ryzen 9 has a prolonged 300s semi-turbo state where it sustains 42W power until thermal saturation of the laptop. During this period, with similar power consumption to the 11980HK and also quite similar thermal results of around 80-83°C, both platforms seem to be quite similar – except for the fact that AMD Zen3 cores able to operate at all-core boost frequencies of around 4GHz, while the Willow Cove cores of the TGL-H system operate at around 3200MHz and below. This is an important metric to note as we dive deeper in other results of our test suite.

In more real-world full load workloads such as Agisoft, we’re seeing the i9-11980HK being able to have more aggressive boost frequencies due to the more dynamic and differentiated nature of the workload. Boost frequencies during the heft of the workload reach up to around 4.5GHz which is what Intel advertises as the nT turbo of the chip, while the rough average sits at around 3.5GHz. Towards the end of the test, we’re seeing lower core count boost frequencies reaching the near 5GHz 1-2T advertised boosts of the cores.

Still, what’s relatively concerning is that temperatures are still quite high even when tested in the 45W PL1 mode, we still see temperatures well in excess of 90°C and peaking at >95°C for transient periods.

(0-0) Peak Power

In terms of peak power comparisons, we see that the chip goes up to quite high transients, and has PL2 configurations of around 85-90W. Due to Tau and the turbo period here being only a mere 5 seconds, it shouldn’t affect thermals too much, and should give the system very good responsiveness, even though it will come at the cost of power and battery life.

Unfortunately, due to the embargo and extremely limited time we’ve had with the system we haven’t yet tested more power scenarios, such as 35W cTDP-down or unplugged battery-only behaviour of the platform. We’ll be following up with updates after today’s initial review.

Tiger Lake-H: 8x Willow Cove up to 65W CPU Tests: Core-to-Core and Cache Latency
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  • ozzuneoj86 - Monday, May 17, 2021 - link

    While it is nice that it supports gen 4, realistically you're just getting SSDs that put out more heat, with more power draw, while gaining performance benefits that are only measurable in benchmarks or very specific situations.

    I'm sure file copy performance is much higher, but how fast do you need that to be? Assuming you're copying to the drive itself or maybe to a Thunderbolt 4 external drive, it is the difference between copying 1TB of data in 2 minutes versus 6 minutes. You can (theoretically) completely fill a $400 2TB SSD in 4 minutes with gen4 vs maybe 12 minutes with Gen 3. If someone needs to do that all the time, then sure there's a difference... but that has to be pretty uncommon.

    For smaller amounts of data, any decent nvme drive is fast enough to make the difference between models almost unnoticeable. For the vast majority of users, even a SATA drive is plenty fast enough to provide a smooth and nearly wait-free experience.
    Reply
  • mode_13h - Monday, May 17, 2021 - link

    > realistically you're just getting SSDs that put out more heat, with more power draw,
    > while gaining performance benefits that are only measurable in benchmarks
    > or very specific situations.

    Exactly. Thank you.
    Reply
  • mode_13h - Monday, May 17, 2021 - link

    > Assuming you're copying to the drive itself or maybe to a Thunderbolt 4 external drive

    Oops! TB 4 is limited to PCIe 3.0 x4 speeds! So, it'd be little-to-no help there!
    Reply
  • Calin - Tuesday, May 18, 2021 - link

    Well, you could copy full blast to an external drive and have plenty of remaining performance to do other storage intensive things - that's assuming your external drives is fast enough to suffocate PCIe 3.0 x4, and your internal drive is faster still. Reply
  • mode_13h - Thursday, May 20, 2021 - link

    > Well, you could copy full blast to an external drive and have plenty of remaining performance

    I'm not one to turn down "free" performance, but PCIe 4 uses significantly more power. In a laptop, that's not a minor point.
    Reply
  • inighthawki - Monday, May 17, 2021 - link

    Sequential read and write speeds are basically just flexing. Very few people actually ever make significant use of such speeds in a way that saves more than a second or two here or there. Most laptop users are not sitting there copying a terabyte of sequential data over and over again. Reply
  • The_Assimilator - Monday, May 17, 2021 - link

    There is no laptop chassis on the market that can adequately handle the excess of 8W of heat that a PCIe 4.0 NVMe SSD can dissipate. Reply
  • Cooe - Monday, May 17, 2021 - link

    You're not getting those kind of speeds sustained in a laptop without RIDICULOUS thermal throttling. PCIe 4.0 in mobile atm is just a marketing checkmark & nothing more. Reply
  • Calin - Tuesday, May 18, 2021 - link

    It allows faster "races to sleep" for the processor. And, since the Core2 architecture, the winning move was "fast and power hungry processor that does what it must and then goes to a very low power state". This gives you very good burst speed and low average power - as soon as you finish, you can throttle everything down (CPU, caches, SSDs, ...) Reply
  • mode_13h - Thursday, May 20, 2021 - link

    > It allows faster "races to sleep" for the processor.

    Are we still talking about PCIe 4? I don't think it works like that.

    > since the Core2 architecture, the winning move was "fast and power hungry processor that does what it must and then goes to a very low power state".

    No, it's more energy-efficient to run at a slower clock speed. There's a huge difference between the amount of energy used in turbo and non-turbo modes. As it's far bigger than the performance difference, there's no way that going to idle a little sooner is going to make up for it.
    Reply

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