[bnieuwen]

Actually Phoronix has power benchmarks for the ACPI power profiles[1]. Seems like a boost to ~28W or so with a long term average of 22-23W.

(Note that this is SoC package power instead of the full laptop though, but that is pretty typical, so no idea what the 22W was for comparison.)

[1] https://www.phoronix.com/review/ryzen7-6850u-acpi

[hajile]

I don't believe those numbers.

The 4800U hit north of 65w in a NUC device[0]. The 5800U hits 52w in a laptop[1]. AMD runs their chips hot.

TSMC N6 is a 7nm++ node. The even more advanced 5nm node only offers either 15% performance increase OR 30% power reduction vs N7. The 6850 clocks 10% higher, so the power shouldn't be dropping AT ALL.

The 6850H has an identical turbo clockspeed of 4.7GHz and a TDP of 45w with real-world power consumption according to other reviewers being north of 65w. The base clocks for these chips is 2.7 and 3.5GHz respectively.

In the case that they really are getting those numbers, they are certainly only at base clockspeeds (2.7GHz) which raises the impossible question of how Zen 3 suddenly got such a huge performance per clock advantage going from desktop to mobile.

The numbers simply do not add up.

[0] https://www.anandtech.com/show/16236/asrock-4x4-box4800u-ren...

[1] https://www.notebookcheck.net/R7-5800U-vs-E-2186M-vs-R7-PRO-...

[bnieuwen]

As the sibling said those numbers are very configurable. e.g. around the x86 handhelds there are tinkerers running their U/P class chips at anywhere from 5W configured to 30+W configured (and with the appropriate cooling could totally go to 60W+ if configured to do so. Silicon-wise there is very little difference between AMD's U and H class chips, mainly just stuff like binning and some configuration in the firmware). Typical reasons to configure this would e.g. be cooling or battery restrictions from the OEM.

Furthermore note there is a difference between SoC package power and power pulled from the wall. That depends on the rest of the device, but 5-10W isn't unreasonable. (So e.g. at 22W package power, pulling ~32W from battery is pretty common). Looking at the detailed graph in the NUC review, that difference is particularly large though, the package only pulls <20W in steady state and maybe 30W at boost[0], but this device somehow seems to have significant power draw coming from somewhere else, this is pretty atypical wrt laptops & battery draw at least.

I'm not sure what performance per clock advantage going from desktop to mobile you're referring to? The mobile chips are slower due to the lower max boost and power limits, but due to non-linear power scaling it tends to be not that* much worse than the desktop parts.

As an aside I find the Anandtech Zen3 review[1] a pretty good resource when I want to have a clue about reasonable clock/power expectations on zen3 (though it is only a single workload)

(Also not sure where the 52W claim comes from, my searching on the linked page seems to yield no results?)

*: With the notable exception that pre-6000 series AMD had some horrible delay clocking up the cores when on battery, hitting short tests like geekbench. That said even on AC the chips should be adhering to configured power limits.

[0] https://images.anandtech.com/doci/16236/wm-aida_power.png [1] https://www.anandtech.com/show/16214/amd-zen-3-ryzen-deep-di...

[wmf]

Firmware can set the power limit to whatever it wants. With the exact same processor, one computer may hit 65 W while a different one is limited to 28 W. There's also huge diminishing utility when it comes to power, so it's possible that the chip is only slightly slower at 28 W than at higher power.

[Delk]

I highly doubt those 50 or 60 watt examples are representative of the power use of those U-series CPUs in a 13" laptop. Perhaps it has been configured differently in a NUC.

Anecdotally, my work laptop has a previous-generation Ryzen 7 5850U (8 cores, 16 logical) in a 14-inch ThinkPad chassis. I just tried a 16-thread xz compression on it a few times and eyeballed the average power use with powertop. The baseline power with no load (except for what little idle load there was from whatever I had open) of the entire system was around 5 W with display brightness at a minimum. The battery discharge rate rose to between 21.5 and 22.5 watts for the couple of minutes the compression took.

This was on battery since I had no tools for monitoring power use at hand otherwise. (Turbostat reports detailed per-core and per-package wattage from the CPU at least on Intel but the distro I've got for work apparently doesn't have that packaged and I'm not going to be hunting for a source package for this.)

However, the compression took pretty much exactly the same amount of time on AC, so I doubt having it on battery affected CPU clock rates significantly.

A 13" laptop chassis would also have serious trouble getting rid of 50 or 60 watts of prolonged heat production from the CPU.

Also, where did you get the 52 watts in a laptop figure? The only reference to 52 on that page w.r.t the 5800U that I can find is a results of 51.9 points per watt, whatever those points are, in some kind of a power efficiency test. The power consumption test above that reports 42.9 watts, measured with an external monitor, so probably including more than the CPU. I also can't immediately find a reference to what kind of a chassis the CPU was in, laptop or otherwise.

> raises the impossible question of how Zen 3 suddenly got such a huge performance per clock advantage going from desktop to mobile

What kind of a PPC increase did Zen 3 get going mobile? I've only read about PPC comparisons between Zen 2 and Zen 3.