Investigation: Why is Bootcamp so much worse on the 2020 Air?

[RiaKoobcam]

I've owned a 2020 i5 MBA and currently own a 2020 i3, and Bootcamp has been a nightmare on both compared to the 2019. Mostly in terms of battery life - you can watch it tick down before your eyes. But there are also issues in regards to realising the Ice Lake/Iris Plus performance boosts, making the Windows experience functionally the same as on the less powerful 2019.

So, the easy answer to 'why is Bootcamp not very good' in any discussion is 'because Apple doesn't bother optimising drivers', and whilst that's true it's not exactly helpful to people who require Bootcamp and Windows 10 for whatever reason.

I've been doing a fair bit of work this weekend and I've identified some issues, if not fixes just yet.

Partially Solving Apple's Driver Issue

First and foremost, I'm not aware of any OEM who does an excellent job with out of the box drivers, but Apple really takes the cake. The Windows Support Software package that is installed after a Bootcamp partition is made contains some drivers from 2006, out of date drivers for the Iris Plus GPU, and no software to run for updates and install them.

So I did, manually, and (especially with updated Intel drivers) noticed increased performance in graphics, from colour reproduction to hardware-assisted rendering of web pages. It's not a silver bullet, but it does offer noticeable improvement - it's just a shame Apple makes this so hard to do.

I normally avoid non-OEM driver updaters like the plague, but given Apple doesn't provide a solution, Driver Booster is the best option. It doesn't install a bunch of third party crap and even though it bugs you to get the paid version, you're able to accomplish a lot with the freeware trial.

The big problem - processor C-states and battery life

The 2019 Macbook Air on Windows 10 is able to comfortably get 9 hours battery life doing simple tasks. The 2020 (i5 and i3, as I've tested them) is barely able to hit 6.

After a lot of messing around and using Throttlestop (not recommended unless you have experience undervolting Intel CPUs/Windows 10 tweaking in general), I think I've been able to identify the big issue with the help of some very smart people over at Notebookreview.

Probably the easiest way to think of C-states is like gears in a manual car. The lower the gear (C-state), the more direct power you're able to give a particular task, but also the less efficient your fuel consumption (battery) is.

Intel's datasheet for Ice Lake chips (published April 2020) states that the 10th gen chips should all have a full gearbox - in this case, access to C0 (launching), C2 (hard work), C3 (light work), C6 (cruising on the highway) and C7 through to 10 (your engine is now so efficient you're barely using fuel).

Unfortunately, the 2020 MBA running Windows 10 can only access C2 and C3, meaning the processor is drawing much more power than it should and is being prevented from entering deeper sleep states. For comparison, the lowest C-state the Y-series 8th gen chip in the 2019 MBA can enter is C6, but it parks about 90% of its load there, making for very efficient running.

Without access to C6, the 2020 MBA running Windows is like constantly driving in second and third gear - sure, it's powerful and responsive, but it's incredibly energy inefficient.

I'm doing some work to attempt to identify a) if this problem can be solved and b) if so, what's the best method. On paper, the 2020 i3 should easily be able to match or come close to the 2019 i5's battery performance and longevity on Windows, so if I find any resolution to this I'll update the post.

For now, though, this is the result of extensive testing and a lot of assistance from others. Hopefully it helps people who (like me) require Bootcamp and are wondering why there's been such a performance drop off between 2019 and 2020. Fingers crossed there's some kind of resolution available with enough digging and testing.

 

[IngerMan]

Great read, thank you for the informative post. I hope you strive ahead and solve the issue.

 

[Bones13]

My question would be : is the C state being controlled by the OS or the BIOS? Is it just more noticeable in BootCamp? Seems that, if it is a BIOS issue, that solving it would be of benefit even to those that don't utilize Windows on their MacBooks.

I have an i7 Razer for Windows and gaming, but ordered the MBA for actually carrying around everyday, and keeping track of things.

 

[edubfromktown]

Might the display being up to ~30% brighter on MBA's running Windows also drain the battery faster as well?

 

[RiaKoobcam]

My question would be : is the C state being controlled by the OS or the BIOS? Is it just more noticeable in BootCamp? Seems that, if it is a BIOS issue, that solving it would be of benefit even to those that don't utilize Windows on their MacBooks.

I have an i7 Razer for Windows and gaming, but ordered the MBA for actually carrying around everyday, and keeping track of things.

It's not just more noticeable in Bootcamp, no. There's a way to prove it.

Although you can't measure C-states in MacOS, Intel Power Gadget reports the PKG Power Draw as around 0.3w on idle (which is great, similar to the 2019 MBA's 0.4w on Windows and MacOS). Compare this to the 2020 MBA Windows figure of 3.3-4w.

According to the C-state folks, this strongly suggests the deeper C-states that enable efficient running are available on MacOS, but not made available in Windows.

Still trying to work out if it's possible to change this and if so, how.

Might the display being up to ~30% brighter on MBA's running Windows also drain the battery faster as well?

Hey good point and great pick up. I did think of that quote from the review when I first started down this road. Sitting the 2019 and 2020 alongside each other, on Windows, 50% brightness is as many nits on the 2020 as 100% brightness is on the 2019.

So, for the purposes of my tests, I've been using 50% brightness as 'max brightness' to try and make the comparison as fair as possible, and despite that, the battery life is still, at best, halved.

 

[maxkwok906]

One of the biggest issues for my 2020 i7 16GB MBA on bootcamp was the trackpad, but luckily, I was able to fix it using some custom precision drivers. (https://ligstd.visualstudio.com/App...d=3824&view=artifacts&type=publishedArtifacts) (https://github.com/imbushuo/mac-precision-touchpad) I hope these help.

Personally I don't find the battery drain on bootcamp that bad, it seems about the same as my older 2015 MBA.

 

[RiaKoobcam]

One of the biggest issues for my 2020 i7 16GB MBA on bootcamp was the trackpad, but luckily, I was able to fix it using some custom precision drivers. (https://ligstd.visualstudio.com/Apple PTP Trackpad/_build/results?buildId=3824&view=artifacts&type=publishedArtifacts) (https://github.com/imbushuo/mac-precision-touchpad) I hope these help.

Personally I don't find the battery drain on bootcamp that bad, it seems about the same as my older 2015 MBA.

That's awesome - thanks for those drivers, I'll give them a go.

Would you (or anyone who is running Bootcamp) mind providing some data for my investigation?

Basically, I need to see if anyone is able to achieve processor deep sleep states (for Macbook Airs, the state is called C6) when running Windows.

The easiest way to do this is to run Throttlestop, which, although it's used for modifying clock speeds etc, we won't be doing.

What would really help is if people could the Visual Studio packages that underpin Throttlestop (they come with Windows Update anyway, these are just smaller files):

The two files you will need to install:
x64 file name: vcredist_x64.exe
x64 file direct download link from Microsoft: https://download.microsoft.com/download/2/E/6/2E61CFA4-993B-4DD4-91DA-3737CD5CD6E3/vcredist_x64.exe

x32 file name: vcredist_x86.exe
x32 file direct download link from Microsoft: https://download.microsoft.com/download/2/E/6/2E61CFA4-993B-4DD4-91DA-3737CD5CD6E3/vcredist_x86.exe

And then run Throttlestop 8.74 Beta, available from: https://www.techpowerup.com/download/techpowerup-throttlestop/

If you extract the files and run them, it won't install anything to your Mac, or change anything unless you turn it on. All we need to see is if there is any activity in the C6 package state.

So what we're looking for is in the below screenshot:

If anyone with a 2020 MBA running bootcamp is able to quickly post their results, and if somebody is able to access a C-state deeper than C2 and C3, that means it's at least possible. From there, once I've figured out how to replicate it, that's three-to-four hours of extra battery life on Windows (or potentially more, given the Ice Lake chip)!

 

[RiaKoobcam]

Alrighty friends, looks like I'm going to have to admit defeat on this one for now. I've spent the last week digging around in every single driver for every single device that could be responsible for blocking lower C-states and killing the battery life in Windows, without success.

If any future user is able to access a C-state lower than C2/C3 in future, please post here, but at this stage it'll probably take a driver fix from Apple (and those are about as rare as Halley's comet on the Windows environment).

What's particularly frustrating about this is that the Ice Lake chip inside this notebook is capable of reaching C10. The 2015 Macbook Air I've been testing side by side on is able to get as low as C7, which means its package power draw, like the 2019 Macbook Air, is around 0.4w in Windows. Good enough for ten hours at 250 nits browsing/streaming/whatever.

Compare this with the 2020 i3, with its minimum draw of 2.2w despite all the tweaking/optimising I've attempted, or the 2020 i5 with a reported lowest idle wattage of 7w in Windows. Not great.

For whatever reason, the drivers for Macbook Air 9,2 (the 2020 series, including the i3, the i5 and the i7) just don't allow for the CPU to shift into 'chill out mode'. This not only impacts on battery life - you lose about four to five hours - but it impacts on the 2020's thermal issues.

By not letting the CPU do what it's designed to do and operate in a very low power state when there's not much being requested of it, it remains hotter for longer in Windows and - whilst providing good performance - will likely lower the chip's overall life cycle. Kinda like wearing out your transmission by highway driving in third gear.

A very frustrating issue that'll affect a lot of users who aren't signed up to MacRumors, but, as we know, Windows isn't exactly the priority (or even a priority at all) for Apple.

Like a lot of things with the 2020 Air, I don't think it's unreasonable to expect a series upgrade to perform at least as good as the previous generation - let alone models that were released five years ago.

 

[macintoshmac]

I believe that BootCamp drivers would be updated to incorporate the new 2020 Air hardware soon. I might be wrong on this, but since 2019 works just fine, it’s possible The drivers aren’t updated for 2020 Air just yet. They might release around the time of new macOS. Lightly-informed speculation.

 

[RiaKoobcam]

I believe that BootCamp drivers would be updated to incorporate the new 2020 Air hardware soon. I might be wrong on this, but since 2019 works just fine, it’s possible The drivers aren’t updated for 2020 Air just yet. They might release around the time of new macOS. Lightly-informed speculation.

I want to believe, but such little care is given to Bootcamp drivers and support that I don't really hold out much hope.

The last Bootcamp update broke my 2019 MBA's keyboard back light and still hasn't been rectified. The one before that (6.0) broke the Function key on my 2015.

I have to spent about 40% of my time in Windows so I've gotten used to stuff just randomly not working, but never something this big or detrimental to performance before.

I really hope C-states and power regulation are implented in new drivers (if they're coming), but my experience has led me to a) not expect that any time soon and b) expect any fixes to break something else

 

[Flix Bergeron]

Wow...I'm late to the party but after a week of searching the internet and learning about clock speeds, underclock, undervolt, c-states and all those things (which I knew nothing about a week ago) I finally find this thread that describes and explains EXACTLY what I've come to understand.

So first of all its not a 2020 problem I think. I'm running Bootcamp windows 10 on a Macbook Pro Retina 11,2 (2014) and I have the same issue exacly. 2.2Ghz. 3.2 Ghz turbo.

By default, Windows will always run at 3.2Ghz. Of course that's draining the battery a lot and adding heat/fan noises.

If you adjust the performance settings (anywhere between 5 % and 100 %) that will change clock speeds BUT clock will never go lower than 2.2Ghz, even if there is nothing at all going on (idle). For comparison, in Mac OS the CPU will lower its clock to 800mhz approximately. I don't have the infos in voltage or power (watts) but, just like you mentionned in the first post there is a big difference in power consumption that's verifiable. (This eliminates a possible wrong reading. Also did many tests with different tuning/analysis softwares)

Disabling turbo boost does the same basically, it will never go down lower than 2.2, but it won't boost higher either.

I've manage to underclock with Intel extreme tuning utility, which works (I can set the clock to anything between 1.5 and 3.2), but then the problem is it doesn't ramp up if under load. This is helpful to save battery or prevent heat or throttling, but then you don't have performance when you could need it.

I'm new to all this. I still need to try more things in Intel utility and/or throttlestop, but any extra help would be great if this conversation is still active. I could also post screenshots of tests and benchmarks so we can all understand better and maybe find a solution.

Cheers

 

[Flix Bergeron]

Oh....well f*** me......i just figured it out. Veeeery simple. And i'm 99% sure i tried this before and it didn't work...but between reboots and installs and other things...maybe it did...maybe it didn't. I'll never know. Anyways...for my system what works is....

-Throttle Stop
-Set profile to power saver (probably works if you do it in the windows power saving options too, but i'm not gonna try)
-And.....that's it. Save
-Can still disable turbo, or not, both modes work fine. In both cases on idle cpu clock will lower to 1.2, 1.4, 1.6Ghz, anywhere around that. Even as low as 800Mhz.

Hope this can work on your 2020 mbp also.

 

[RiaKoobcam]

I'm glad that worked for you, but that wasn't the issue with the 2020 Air - I think you're conflating CPU clock with power wattage, the latter having a far greater effect on battery life.

For whatever reason, Apple has locked C states lower than C2 on the 2020 Air running Bootcamp, meaning nobody's ever going to get better than five hours unless brightness is one notch above blank and no programs are running. C3 and C6 - both available on previous Intel-based Macbook Airs - aren't available.

After trying a million driver updates (the usual reason for C-states being locked - not even Windows OEMs optimise for Windows power saving properly all the time), I still couldn't get them unlocked. It'd probably take a major driver update from Apple to give the MBA 2020 the same battery/power performance it got in previous generations, and with the move to Apple Silicon, I doubt they give a flying ****.

Sucks for users like me who have to use Windows half the time but enjoy Mac hardware/MacOS as a personal OS, but I imagine we're a pretty small segment. Frustrating, because it's a relatively easy fix, but unfortunately it's not one that can be done without Apple pushing an update.

 

[gaanee]

Thanks for reporting your findings.. very useful write up.
Is this issue specific to Air or even MacBook Pro also uses the same drivers and hence face the same issue?
I have been considering either MBA or MBP with Intel before Apple switches to its own Silicon mainly for being able to use Windows through Bootcamp.. I guess I will wait to see if Apple updates its Windows drivers or just get a Windows laptop.

I'm glad that worked for you, but that wasn't the issue with the 2020 Air - I think you're conflating CPU clock with power wattage, the latter having a far greater effect on battery life.

For whatever reason, Apple has locked C states lower than C2 on the 2020 Air running Bootcamp, meaning nobody's ever going to get better than five hours unless brightness is one notch above blank and no programs are running. C3 and C6 - both available on previous Intel-based Macbook Airs - aren't available.

After trying a million driver updates (the usual reason for C-states being locked - not even Windows OEMs optimise for Windows power saving properly all the time), I still couldn't get them unlocked. It'd probably take a major driver update from Apple to give the MBA 2020 the same battery/power performance it got in previous generations, and with the move to Apple Silicon, I doubt they give a flying ****.

Sucks for users like me who have to use Windows half the time but enjoy Mac hardware/MacOS as a personal OS, but I imagine we're a pretty small segment. Frustrating, because it's a relatively easy fix, but unfortunately it's not one that can be done without Apple pushing an update.

 

[G5isAlive]

Fascinating read, though way over my head. I do have a question though .. what's the problem? ...I don't mean theoretically, I mean practically. Who is affected? What are they doing?

In all this discussion of C state, and coasting along in 7th gear... the point seems to be "Good enough for ten hours at 250 nits browsing/streaming/whatever." Going to assume whatever is anything that does not require any great CPU demand which rules out most things I imagine most people would want to use boot camp for anyway (cough..gaming. cough). In other words, in most low power situations, browsing, why not just use Mac OSX? I would imagine when one IS doing CPU intensive operations (gaming) that being stuck down in C2 and C3 is just fine.

So, the practical problem seems to be restricted to people that do not want to be plugged into the wall (i.e. are on battery) and don't want to use Mac OSX to browse the web but instead want to run bootcamp for even simple things? So why get a Mac?

Not meaning to be argumentative, just, a bit confused on what the practical issue is here.

 

[prism]

I wonder if the new bootcamp release fixes the new MBA problems described in this threat! Anyone who actually uses bootcamp with the new MBA care to comment?

 

[dmccloud]

Most of the problems being described in this thread are actually not even specific to the MBA (regardless of year). I used to run Windows via BootCamp on my 2014 15" MBP, and the fans and processor ALWAYS ran on high. As a result, my 8-10 hours of battery life became under three hours if I was running Windows on the same hardware. After about a year of this, I just picked up a Windows laptop to use for those things I was required to use Windows on, since that would give me the battery life I needed without sounding like a jet taking off from the airport. I tried Boot Camp a few more times since then (most recently in Catalina), and I had the same issues then that I had in 2014-15. I am not convinced that either Apple or Microsoft ever placed a premium on properly managing the fans and power states under BootCamp.

 

[theSeb]

They are indeed not specific to one particular Mac, but will be worst felt on the most thermally constrained Macs.

In Mac OS Apple have tweaked the voltages and fan curves in very specific ways to try and tweak out as much performance as they can from Intel chips whilst trying to keep thermals, throttling, fan noise and performance in some kind of balance without throttling too far below the advertised base clock rate of the CPU.

None of those tweaks are applied to Bootcamp. The result is that voltages are higher and thresholds for throttling trigger sooner. This is why, for example, a Dell XPS with the same CPU as a Macbook Pro easily beats the Mac in Windows.

 

[prism]

So was bootcamp DOA since launch?

 

[prism]

Sounds like this thread is pretty much dead, how depressing!

 

[nobackup]

Any updates. Seems a good way to use the”old” air. Looking to do something for my kids as they “need” windows for school.

 

[mariusmuntensky]

I own a macbook pro 2020 model with the 8th Gen Intel, not a macbook air but the issues I believe are the same for the entire 2020 lineup. What I've found not working:
1. I cannot install Windows 10 old school with booting from a USB drive, despite disabling all the secureboot stuff in Recovery. Setup hangs at the first screen, despite having manually put the drivers in the $WinPE folder and having the AutoUnattend XML file on place. This used to work well on my older 2016 macbook pro model.
2. Installing via Bootcamp works but once in Windows I get several problems: screen auto brightness and manual brightness adjustment stops working after closing the lid+sleep, reopen the lid+wakeup; color calibration in movies is way off meaning the colors are OVER-saturated, especially red; That Smart Charging Apple has implemented in BigSur seems to affect Windows in a bad way, meaning not even at 70%, it does not charge the battery. Somehow this got fixed after a few reboots in Macos and back to windows; bluetooth...old bluetooth issues that Apple failed to fix 'till this day, after resuming from sleep, I cannot connect any headphones. I have to reboot to make it work; Battery life is worse, much worse than on macos.