G750JZ Problem Eye strain from screen flickering that is caused by low PWM frequency

[HyperZ]

I discovered a screen flickering that is caused by low PWM frequency (backlight brightness is controlled with PWM).
See video that I posted on youtube: http://youtu.be/20NB91RNFW8
It may be related to Intel HD4600 GPU, therefore ALL new series of Asus notebooks with Optimus could be affected. So if you have sensitive eyes see notebook/screen in person before you buy.

Please let me know if you have the same flickering with your G750JZ / G750JS / G750JM notebooks:
-set Brightness to 50%
-use cell phone to see it
If you have the same flickering you may get eye strain/headache

[hmscott]

HyperZ wrote:
I discovered a screen flickering that is caused by low PWM frequency (backlight brightness is controlled with PWM).
See video that I posted on youtube: http://youtu.be/20NB91RNFW8
It may be related with Intel HD4600 GPU, therefore ALL new series of Asus notebooks with Optimus could be affected. So if you have sensitive eyes see notebook/screen in person before you buy.

Please let me know if you have the same flickering with your G750JZ / G750JS / G750JM notebooks:
-set Brightness to 50%
-use cell phone to see it
If you have the same flickering you may get eye strain/headache

If you have to use an electronic camera, like the cell phone camera to see the problem, you are seeing the common problem of trying to photograph off of screens with a similar refresh rate as the camera scan rate - if they are just a little off they will "beat" and you will get a slowly scrolling scan line as seen through the electronic camera.

If you are seeing this via the naked eye, then your eye's scan rate is out of calibration, please refer to the manufacturer 🙂

[HyperZ]

I have 5 notebooks at home and NON of them have that flickering.
hmscott
if you do pencil test you can see it too, not only with cell camera, but you have different model than G750JZ / G750JS / G750JM notebooks therefore you may not have such problem.

[hmscott]

HyperZ wrote:
I have 5 notebooks at home and NON of them have that flickering.
hmscott
if you do pencil test you can see it too, not only with cell camera, but you have different model than G750JZ / G750JS / G750JM notebooks therefore you may not have such problem.

I am not saying I don't have the problem, as it is irrelevant.

You are fiddling around with the borderline brightness at the flicker point between one brightness setting and another, that is showing the beat frequency through a similar frequency scan rate. And, the pencil test is what you use to demonstrate / make visible that beat frequency phenomena to observers without an actual camera to look through.

You have discovered a parlor trick, not a hardware problem specific to the new G750's 🙂

https://www.google.com/search?q=laptop+refresh+beat+frequency+at+lower+brightness&ie=utf-8&oe=utf-8&...

You are changing the flash rate as you decrease the brightness, as that is how the square wave controlling the light induces a change in perceived intensity. Reducing the brightness reduces the frequency, and at some point along the setting range, in this case 50%, a beat frequency is induced and you can perceive the wave pattern as the difference between refresh and light on/off frequency.

Many laptops have this same behavior.

At 70hz and above it will be more comfortable, but for now that isn't an option on the new G750's with Optimus as it uses the Intel control panel which doesn't appear to allow custom resolutions with custom refresh rates.

For now all you can do is keep the brightness up high enough, and not at the beat frequency inducing setting to not induce the perceived flicker.

[gazzacbr]

hmscott wrote:
...
At 70hz and above it will be more comfortable, but for now that isn't an option on the new G750's with Optimus as it uses the Intel control panel which doesn't appear to allow custom resolutions with custom refresh rates.
...

does that mean any laptop with Optimus cannot have a 3D screen?

[hmscott]

gazzacbr wrote:
does that mean any laptop with Optimus cannot have a 3D screen?

gazzacbr, have you seen any 3D screen laptops with Optimus? I haven't... because there aren't any, and there won't be any.

"Currently, the 120Hz panel is tied to the Nvidia 3D Vision Enabled SKU, which does not support Optimus. You must choose a 60Hz panel to get Optimus. The absence of Optimus on the 120Hz (3D stereo) configuration is an Nvidia imposed restriction. It is not something Dell chose or desired. We tried hard to get Nvidia to support this, but it was not possible for Nvidia to overcome the technical challenges." - Dell

It's actually a limitation of the Intel IGPU Output Controller, it can't pass the bandwidth required to support 3D, so you either connect directly to the discrete Nvidia GPU, or you are limited to what the Intel IGPU Output Controller can do.

http://www.likelyanswer.com/14311906/M17x-R3-Integrated-Intel-Sb-Gpu-is-Disabled-Woptional-120hz-3d-...

Here is a nice video describing the 60hz limit of Optimus, and why 120hz panels aren't supported.

http://www.youtube.com/watch?v=RJ3IRvCkllg

More details:
http://forum.notebookreview.com/alienware-17-m17x/549958-m17x-r3-integrated-intel-sb-gpu-disabled-w-...


So we know that 120hz isn't supported with Optimus, and it is currently limited to 60hz, but I don't know if Optimus can be made to allow tweaking the refresh rate a little past 60hz or not.

[KoolASUS]

Hello hyperZ,

this flickering is common to all G750.
one workaround was to increase the refresh rate, but it doesn't work with optimus.

i doubt there will ever be a fix. (Asus never did for the previous G750)

you're right : I've never seen that on other laptops (whose screen have a 60Hz refresh rate, but are perfect). Alienware products don't show that. (no mention ever in their forums)

some people don't notice this, some people can't bear it.

[hmscott]

KoolASUS wrote:
Hello hyperZ,

this flickering is common to all G750.
one workaround was to increase the refresh rate, but it doesn't work with optimus.

i doubt there will ever be a fix. (Asus never did for the previous G750)

you're right : I've never seen that on other laptops (whose screen have a 60Hz refresh rate, but are perfect). Alienware products don't show that. (no mention ever in their forums)

some people don't notice this, some people can't bear it.

Lots of other notebooks use PWM and have the same low brightness problems, you just have to do a few google searches.

Macbooks
https://www.google.com/search?q=macbook+pwm+flicker&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:off...

Alienware/Dell
http://www.youtube.com/watch?v=Dk4ckdQ9rvE
https://www.google.com/search?client=firefox-a&hs=H2c&rls=org.mozilla:en-US:official&channel=sb&scli...

samsung
https://www.google.com/search?client=firefox-a&hs=H2c&rls=org.mozilla:en-US:official&channel=sb&scli...

general
https://www.google.com/search?num=50&safe=off&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial&ch...

Find the brightness level that intersects with your desire for no flicker and correct brightness. Hopefully there is a setting that resolves both desires. 🙂

For those of us without Optimus, we can change the refresh rate, and also put the brightness all the way up - and set Nvidia control panel to adjust contrast - fixed signal lower contrast to attain desired "brightness"

[Master_Po]

HyperZ wrote:
I discovered a screen flickering that is caused by low PWM frequency (backlight brightness is controlled with PWM).
See video that I posted on youtube: http://youtu.be/20NB91RNFW8
It may be related with Intel HD4600 GPU, therefore ALL new series of Asus notebooks with Optimus could be affected. So if you have sensitive eyes see notebook/screen in person before you buy.

Please let me know if you have the same flickering with your G750JZ / G750JS / G750JM notebooks:
-set Brightness to 50%
-use cell phone to see it
If you have the same flickering you may get eye strain/headache

... It's also like this on all of my previously owned 5 x ASUS G74VW. But clearly shown without using camera, and 100% brightness.

But luckily for me, I don't really see it that much on my ASUS G750JZ.
Perhaps a little, specially on this forum where it's all black.

[HyperZ]

I just came back from the store, and I have posted video on YouTube:
note: in the video you will see that I change brightness from max to min

-Asus G750JH-DB71 (with screen CHI MEI N173HGE-L11 (CMO1720)) = Flickering the same way as my new G750JZ (with N173HGE-L11 (CMO1720)" or "AUO B173HW01 v4 90% glossy screen)
http://youtu.be/6bGDIUe9Iko

-Alienware 18" = It has PWM Flickering, but NOT to much.
http://youtu.be/i0hi_58xtfs

-Toshiba Qosmio X75-A7180 17.3" (AUO B173HW02 V0 / AUO209D) = NO PWM Flickering at all!
http://youtu.be/Z8vRNoSqYOY

-Asus K550LA-MS51T 15.6" = NO PWM Flickering at all!
http://youtu.be/UKehb13tL38

Result:
G750JH-DB71(see video above) flicker the same way as my NEW G750JZ, its almost a year(may be more) and Asus didn't do anything about it!