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Venue 8 Pro + Windows 10 = power drain / CPU throttling problem
I have reported this already about 8 months ago while being in the insider program over the Microsoft feedback tools, so I am very pleased that this bug still is present in the final version...
The problem is simple, and I have two friends whos Venue 8 Pro show the same behavior after upgrading to Windows 10.
I have tried a clean install too, I have tried the newest drivers for the Intel Z3700 series Dell had put online for Windows 10, without any success.
The problem is simple:
1.) Let Windows idle
2.) Open TaskManager (or for example CPUz) and monitor CPU throttling
Under Windows 10, the CPU 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 (normal) 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.
Heres a video showing problem 1:
https://dl.dropboxusercontent.com/u/14937594/win10cpubug.mp4
You can see how the CPU throttling is not working properly always staying at mid-highe throttling state of the Atom CPU. Normal throttling would be 0.8GHz.
Here is how it should correctly be:
https://dl.dropboxusercontent.com/u/14937594/normal-idle-throttling.mp4
(sorry for the bad quality)
On my desktop PC and my Asus Ultrabook the throttling work fine, so it seems a problem related to the Atom BayTrail drivers under Windows 10 or a combination of things.
mkdr
123 Posts
0
October 16th, 2015 10:00
I can confirm this fixes the toggle bug and also Win10 seems to be a bit faster too here and there, and had faster boot time/login, I wonder if they just removed the cpu lock of core #0 and #1 they introduced a year a ago and leaded to this issue under Windows 10, will test connected standby drain over next day.
No will not thank anyone at Dell, they didnt say anything on this thread to no one, they just fixed it silently after months. I Thank myself that I have reported this issue where no one else did.
mkdr
123 Posts
0
October 17th, 2015 03:00
Testing so far leads to a way better drain in connected standby of about 0.5/h, which is fine, but still not as good as under Windows 8.1 of about 0.35/h. The marge by MS btw is 0.3/h.