Windows 10: CPU throttling not working properly, bad standby drain

Just wanted to write this thread so other people can decide if it's worthy to switch to Windows 10 (on a tablet or laptop). I guess it's fine for a desktop and it will run really nicely, however I dont upgrade on a tablet or mobile device, until maybe a few months into the future.

There seems to be a bug with power-stepping or throttling, maybe connected with Intel Turbo Boost. Ive noticed this already 7 months ago, when I put an insider build on my Dell Venue 8 Pro tablet, and Ive reported it back then a few times.

Three days ago I tested 10240 build, clean install of course, which will be RTM, again on my Venue, and the bug is still present.

The problem is simple: Windows 10 doesnt switch to the CPUs lowest power state, and always idles between 1.3 and 1.8GHz (for my tablets CPU which is a Atom BayTrail). It never goes down to 0.5 or 0.8GHz even if there's 95-99% idle.

Ive monitored this via task manager but also CPUz.

The 2nd issue is the power drain in connected standby mode, which I also monitored over 48h. The result was a drain of about 1.1mW/h, which is bad and way outside the norm, Microsoft gave for connected standby, which should be at about 0.3mW/h.

You can google this and there are other reported by poeple way back to 9 months who reported this too, but oh well, it wasnt fixed until now it seemed or maybe not for all processors/models.

So Ive switched back to Windows 8.1, and did the same power testings, resulting in a drain of 0.35mW/h over 12h, which is fine.

I guess it's a driver issue maybe with Intel power policy drivers, or even something with Windows 10 handles things. I hope this will get fixed soon, otherwise I wont upgrade with my tablets or laptops to Windows 10.

:)

 

Lower CPU power throttling states not working correctly for Intel Atom BayTrail tablets

First thing, I am really annoyed by this, because I have reported the bug several times over the past 0.8 years, yes, years, through the insider tools. First I noticed this bug when I installed insider build 9xxx on my Dell Venue 8 Pro like 7 months ago.
It was easily reproducible:

1.) Let Windows idle

2.) Open TaskManager (or for example CPUz) and monitor CPU throttling

The bug is simple: Under Windows 10, the throttling seem to be broken for at least an Intel Atom BayTrail (3700 series). The CPU always stays around 1.3-1.7GHz @ 1-3% CPU load. The same idle behavior under Windows 8.1 results in the processor correctly using
it lowest energy states between 0.5-0.8GHz. This results in a way noticeable faster battery drain.

2nd bug, mostly related: The battery drain in connected standby is about 3 times higher (~1.1mW/h), compared to Windows 8.1 (~0.33mW/h). The normal drain, by Microsoft itself, is 0.3mW/h for a device supporting connected standby mode.

Now that Windows 10, maybe... may be, that Microsoft devs will look into this, because it has huge impact on using a mobile device.

I have tested it on my Ultrabook and my Desktop too by now, and there it seems to work normally, and the CPU goes correctly to its lowest throttling state in a low idle environment.

 

Battery drain since the new firmware

One of the most common reasons for N900 high battery drain while sitting in standby is a known bug that causes pluseaudio not to unload properly sometimes after a phone call is ended. To see if that's the problem, just open a terminal type 'top' and hit
enter. If pulseadio is listed at or near the top of the active services (on the right) and is consistently using 1-2% of CPU, the pulseaudio bug is the problem with battery drain. Or you may see something else is draining the battery, which is another conversation.



My N900 usually idles at about 1-3% total CPU load, it's normal to fluctuate some. I've never let it sit unused long, but at that rate it can sit overnite and still have a full battery in the morning. Consistently higher CPU usage than that will reduce
standby time from somewhat to drastically depending on the total CPU load.



To correct the pluseaudio bug you have 2 choices:



1. Wait for the 1.2 update, due any day now. It will include a bugfix for this.

2. As root, type 'killall pulseaudio'. The service will auto-restart and you should be good to go.



If you don't know what #2 means, wait for the update.

 

Chipset drivers probably replaced by Microsoft generic - not the best - Latest Intel Chipset Device Software - Windows 10 Forums for intel. For others see sticky threads at top of Drivers and Hardware forum.