New MacBook Pro 13-inch 2018 Model still affected by Thermal Throttling Issue during CPU or GPU intensive Tasks
Update December 21, 2018:
Recently, under MacOS Mojave with the latest updates, also with SMC, PRAM and NVRAM reset, the thermal control issues has surfaced again: The fan kicks in with high speed early and the CPU downclocks to 0.4 GHz although no high temperatures are reached and the system freezes up to a minute occasionally.
While the first firmware update at least improved the situation on MacOS, the second update is claimed to improve the situation under Windows with Bootcamp as well: https://egpu.io/forums/mac-setup/macos-high-sierra-10-13-6-supplemental-update-2-for-macbook-pro-2018/ However I still get hangs occasionally on Bootcamp as well.
Is the 13 inch model affected by thermal throttling issues as well?
We all read about the thermal throttling issues with the 2018 MacBook Pro 15" Intel Core i9 hexa core. I recently ordered a 2018 MacBook Pro 13" (Intel Core i7 quad core 2.7 GHz model), so I worried whether it will have the same issue. The CPU clock indeed is capped at 4GHz and when reaching 100°C starts severely throttling the CPU clock speed, sometimes to as low as 400 MHz (!).
Stress testing the MacBook 2018 13 inch model
The 2018 MacBook Pro 13 inch model I ordered is the 2.7 GHz Core i7 quad core with a specification of 2.7 GHz baseline and 4.5 GHz TurboBoost clock speed.
Under high load the model boosts above the baseline of 2.7 GHz but seems to be capped at 4.0 GHz instead of the advertised 4.5 GHz, with occasional drops in frequency when reaching 100°C (left side).
Under stress (in this case GeekBench 4 CPU Benchmark + iCloud sync processes like “bird” + Kaspersky Antivirus processes maxing out the CPU) the temperature hits the 100°C ceiling and severe throttling kicks in: The clock speed reportedly goes down to 0.4 GHz (!).
I cannot reproduce this reliably. Usually the drops would be not below 1–2 GHz, but still this is not acceptable. I think it probably has to do with the four cores being maxed out at the same time for a longer period of time without giving the CPU a break to ventilate. I will keep an eye on the issue and consider returning the device.
Windows 3D performance testing with Nvidia eGPU
I noticed the thermal problem first in Windows with Bootcamp when benchmarking eGPU 3D performance with an external graphics card (Nvidia GTX 1070 Ti in an Asus XG Station Pro eGPU enclosure) attached with Thunderbolt 3 under Windows 10 64 bit. The framerate would drop from 120 to 8fps (frames per second about every 4 seconds for about a second before ramping up again. With Intel Power Gadget on Windows I saw CPU frequency drops to 400 MHz.
I could eventually resolve the framerate drops issue with power management limits for the CPU of min. 85% max. 90%, strongly indicating a link to the thermal throttling. (In addition with headphones connected the sound would lag — an issue not seen when using the built-in speakers. However this is likely unrelated.) So I wondered whether this is a Windows only issue and booted back into MacOS. There, I saw the same issue when the CPU is already maxed out and the CPU temperature close to 100°C and you start a heavy CPU benchmark like GeekBench 4.
I wondered whether the issue could be bootcamp related, but I don’t think so. I have not modified the MacBook’s firmware in any way. The system boots fine with an eGPU if you connect the eGPU Thunderbolt cable only after the Windows logo shows up and the loading spinner starts spinning. However you have to prepare the Windows 10 installation a bit with DDU (device driver uninstaller), disable PCI Express Root Port 9 and installing some drivers for the Thunderbolt bus, the Nvidia graphics and the XG Station Pro.
While the stress tests under MacOS were ran without eGPU attached, I suspect that the additional load of an eGPU created some additional load and heat in the system.
Try before you buy
I had severe thermal throttling issue with the original 2007 MacBook Air (dual core 1.8 GHz) that would even shutdown one core when playing simple Youtube videos. Eventually Apple “fixed” the problem by underclocking both cores to 800 MHz under load so the second core would not shutdown completely. Gravis, the Apple reseller refused to take it back just 3 days after the purchase and after a year of struggle, I got a small refund and eventually sold it at 25% of the price warning the new owner. Luckily, buying through Apple directly at an Apple Store or online, there is a no questions asked 30 days return policy. My suggestion is to use these day wisely and stress test your system in your everyday scenarios as much as you can.
Except thermal issue a great piece of hardware
I am a bit split minded in my opinion about the thin Macbooks — the issue from the beginning has been either low performance or high temperatures and thus thermal throttling issues. The balance with the 2016 models however was much better.
Personally, I love the lightweight design and think it’s still the best laptop out there, and I am willing to sacrifice a bit of performance and a bit higher price for the great hardware and software user experience — as I have been using Windows computers for more than 15 years before switching to MacBooks in 2007 I know why I buy Macbooks. I like the 2016 design update, the great display, precise keyboard and trackpad — even if I prefer tactile keys to the Touchbar.
However I am seriously considering returning this device if the CPU throttling is doing a hard staccato that disrupts real-time use cases. I know it’s difficult to strike the right balance in these highly integrated devices, but I would prefer to have lower clock speeds instead of the sharp performance cliffs with deep drops to 400 MHz. Unfortunately, it seems there is no way to underclock MacOS.
