Hello, I own a Dell XPS 15 9550, I hit sometimes PC8, but it's unreliable, I actually thought it never got below PC3 (with F25 beta). In the second paragraph you wrote: "The deepest power saving state I can get into is PC3, despite Skylake supporting PC8" Where does this come from? I've checked the datasheet you linked, on page 66 (paragraph 4.2.5) there is this: "The processor supports C0, C1/C1E, C3, C6, C7, C8, C9 and C10 power states". Is badly worded, it should say PC{0..10}, on page 69 there even is a description of Package C10 State. On page 70 there is a nice table, PC10 can be reached if PSR is enabled, otherwise only PC8 is supported. I checked then the intel datasheet for H-series mobile processors [1] (like the i7-6700hq I have), the relevant pages are 73-76 (but the table was omitted), but it looks the same. I'm also having an email exchange with another xps 15 9550 linux user, he wrote to me that his system does reach down to PC10, so now I'm trying to get to the bottom of this (I think he's running F24 or 25). [1] http://www.intel.com/content/www/us/en/processors/core/6th-gen-core-family-mobile-h-processor-lines-datasheet-vol-1.html
Power management, mobile and firmware developer on Linux. Security developer at Aurora. Ex-biologist. mjg59 on Twitter. Content here should not be interpreted as the opinion of my employer. Also on Mastodon.
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Skylake PC8 or PC10?
Date: 2016-11-05 03:41 pm (UTC)I own a Dell XPS 15 9550, I hit sometimes PC8, but it's unreliable, I actually thought it never got below PC3 (with F25 beta).
In the second paragraph you wrote:
"The deepest power saving state I can get into is PC3, despite Skylake supporting PC8"
Where does this come from? I've checked the datasheet you linked, on page 66 (paragraph 4.2.5) there is this: "The processor supports C0, C1/C1E, C3, C6, C7, C8, C9 and C10 power states". Is badly worded, it should say PC{0..10}, on page 69 there even is a description of Package C10 State. On page 70 there is a nice table, PC10 can be reached if PSR is enabled, otherwise only PC8 is supported.
I checked then the intel datasheet for H-series mobile processors [1] (like the i7-6700hq I have), the relevant pages are 73-76 (but the table was omitted), but it looks the same. I'm also having an email exchange with another xps 15 9550 linux user, he wrote to me that his system does reach down to PC10, so now I'm trying to get to the bottom of this (I think he's running F24 or 25).
[1] http://www.intel.com/content/www/us/en/processors/core/6th-gen-core-family-mobile-h-processor-lines-datasheet-vol-1.html