Spectre x360 brightness changing. CABC?

[andrewiam_com]

I have the HP Spectre x360 13-4003dx (the $1200 1080p model).  Once in a while (twice a day out of 4 hours of daily usage), the display will dim itself then brighten back up after 10 seconds.  Using the function keys to increase then decrease the brightness does not restore the backlight brightness and quicker than just waiting; the display just gets even dimmer then back to the previous dim brightness until a few more seconds have passed.  I have disabled Adaptive Brightness in the Power Settings of my power plan ("HP Recommended") to no avail.  I suspect the x360 may be using CABC to dim the screen based on the brightness of its content.  Does the Spectre x360 feature CABC?  There is no mention of it in the BIOS, Intel's HD Graphics settings, or the Power Settings.  And where is the x360's brightness sensor?  I want to tape over it to rule out auto-brightness ignoring the power settings. 

[Sparkles1]

Hi @andrewiam_com,

Welcome to the HP Forums!:smileyhappy:

It is a terrific place to find answers and tips!

For you to have the best experience in the HP forum I would like to direct your attention to the HP Forums Guide Learn How to Post and More

I grasp that your display is auto dimming and the function key is not altering the brightness.

Here is a link to HP Notebook PCs - Resolving Problems with the Brightness of the Display.

If you should require further assistance please contact HP support.

Please call our technical support at 800 474 6836. If you live outside the US/Canada Region, please click the link below to get a support number for your region.

World Wide Phone Support

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If this resolved your issue, please select solution provided to help other people to find it.

I hope this helped.

[andrewiam_com]

@Sparkles1
Thank you for replying. I should clarify my question. I can change my laptop's brightness using either the Power Settings or the Function Keys. The problem is that the brightness will fade down (taking half a second) and stay that way for about ten seconds before fading back to full brightness. This is not the same as changing the brightness using Power Settings or the Function Keys nor the brightness timeout because those brightness changes are instantaneous and do not fade. I have disabled Adaptive Brightness but I suspect my x360 is ignoring the fact I changes this setting. To fix this, I would like to tape over the brightness sensor to rule out the possibility that Adaptive Brightness or some other Auto-Brightness feature is still enabled. I cannot find any documentation that shows where the brightness sensor is (and I know there is one because if there wasn't them the Adaptive Brightness setting wouldn't be shown). If you know where the sensor is, or you know about another feature such as CABC that would affect the brightness, please let me know. This is starting to feel like the Dell XPS 13 auto-brightness saga.

[Sparkles1]

Hi @andrewiam_com,

Thank you for clarifying your issue.

I did check for a maintenance and service guide but was unable to locate one.  As the display also acts as a tablet the sensor must be in that section.

For assistance please contact phone support. The link is in my previous post.

Would you be kind enough to post the results so I will have that infomation in case someone else should experience the same difficulty.

Best of Luck!

[andrewiam_com · Accepted solution]

I finally found it!  I didn't see it before because it was called Intel Display Power Saving Technology (DPST) instead of Content Adaptive Brightness Control (CABC).  The setting is in Intel HD Graphics Control Panel > Power > On Battery > Display Power Saving Technology.

[Sparkles1]

Hi @andrewiam_com,

Thank you for the update and I am glad you were able to locate the setting and overcome this issue.

Have a fantastic weekend!