Laptop's simultaneous usage of Battery and power supply

Hello all
still on windows.
my laptop(Asus)has this design that when the graphic card works harder,it needs to use also the battery.
for example:after playing a game with V-sync disabled(in-game setting), the battery can get to 80% ±.
but with v-sync enabled ti loose maybe 1-2%.

my question is:
does Manjaro knows how to handle that,or will the graphic card performance be limited to the power supply only.
or is it something that is taken care by the GPU driver?
or it’s only a matter of; stressing more the GPU causes that to happen automatically?

Hey there, I’m going to start with – I dont know. :sweat_smile:

  • What model of Asus do you have?
  • Can you provide an output of your hardware types?
  • Have you searched the various compatibility matrices that are available around the internet for your device to see how well linux supports it? ← this one is important as there is more to support in a laptop than the graphics. Things like fn keys, keyboard and screen backlight, thermal management, etc.

For example, my Asus GL504G needs a few tweaks from the default install for the FN keys to work – and I need to follow the guides to get my hybrid graphics working properly – but it works, and works very well and while I have never sat there and measured FPS difference from when i switched from the default included Windows 10, gaming is still a nice experience.

As a side note, what you describe seems like such a horrible electrical design it baffles me that somebody would actually design that. To think that you design your system power requirements to be beyond what your main power rail can handle… !?! So, out of my own curiosity, I’d love to know your system model number so I can educate myself as to why this would be.

Lastly, I am no expert in this area, but v-sync would limit the graphics card’s output FPS to the maximum of your display (60hz, 144hz, etc) — so this would not increase your power usage, it could actually decrease it. (Here’s an old article on vSync, Double and Triple buffering and how they work: https:// www.anandtech. com/show/2794 Remove spaces in url)

1 Like

I’m pretty sure this is not handled by the operating system, but by the power delivery chip or something similar. In my opinion the only way to be sure is to test it.

1 Like

This is actually not unheard of. Many laptops have this “feature”.

1 Like

Yeah, since my post i did some reading. From what I’ve read, it’s related to a manufacturer shipping a power adapter that is smaller than the maximum power needs of the laptop. So in that case the laptop will draw upon the internal battery. :man_shrugging:

I also agree that this would be a feature of the hardware, not software.

1 Like

thank you for your answers,

-it’s an Asus Tuf FX705
i7,GTX1050,60Hz monitor,16GB Ram.

-it’s indeed a poor design or choice to send an adapter that can’t support the hardware.
it seems unacceptable and apparently quit common(at least from what i could see)

-with the FPS uncapped the GPU works harder,that’s what i meant.

i hope someone could provide a more conclusive answer
and until then I’ll try and find more specific topics related to my laptop and Manjaro since you got me a bit concerned with ‘thermal management’ and screen brightness.

Looks like Kernel support for the hardware is in place – this is my biggest concern with laptops and Linux – https:// datalinx. io/2019/12/07/asus-tuf-gaming-fx705gd-and-ubuntu-linux/

Also no mentions that I found in a quick search about power issues, or throttling of the GPU.

My advice, give it a shot and report back here your findings. Maybe report on the Arch wiki too: https:// wiki.archlinux. org/index.php/Laptop/ASUS

1 Like

This is something that is usually managed by the EC (embedded controller) of your laptop.
If that is really the case that the machine draws more power than the AC adapter can deliver, the manufacturer did something wrong (in my opinion at least. They might call it “a feature” instead :wink: )


Thank you very much for looking around and also providing the link,
i feel more reassured now especially that the Fx705GD is the exact model i have.

and i really have now idea why they chose to do it this way.

1 Like

It’s a bad move IMHO. Not only does the PSU run HOT but you are also nibbling away at the battery’s charge capacity each time it dips into battery power.

My opinion as well.

My advice would be to get a (genuine) PSU with a higher current rating (same voltage, obviously). I did for my Lenovo and the new larger brick runs only slightly warm for the most part.


Yeah, all to save a few cents in components, I bet. It’s now on my list of things to watch for when buying new laptops. I am sure the manufacturers that do this have reviewed how long that extra stress/heat will degrade the equipment and ensure that the majority of the devices wont fail until after the warranty period has ended. :roll_eyes:


My laptop has a similar feature, but for the CPU. It is configurable in BIOS and works without the need of the kernel.

1 Like

the battery life is indeed my main concern;when it doesn’t hold charge any more,what am i supposed to do?
fortunately batteries are available, but from third party sources that i don’t 100% trust or feel confident to put in the case.
genuine PSU for my model are not available as far as i know from the last light research I’ve done.but if and when needed, I’ll search for one again.

@lrissman after around 10 years I’m done now with laptops,paying more for less and not being able to upgrade.
anyhow i paid for the extended period warranty,so we’ll see.

@ mbb
That’s a weird “feature” :upside_down_face:
i still wonder what’s the purpose behind it,does a 100W higher PSU cost that much more?in any case,this seems unacceptable.

I’m glad to learn from all your answers that it doesn’t seem to be related to the OS but more probably to the mother board components or Bios.
and when I’ll know more I’ll try to report back.


Agree with this obviously disadvantageous cost-cutting being unacceptable; I bought the 90W (20V, 4.5A) from an eBay seller for about GBP £20, to substitute the 65W (IIRC) one which came with the machine and has a crappy adaptor to fit the laptop which was constantly losing contact after a couple of months of use. I’m lucky it didn’t fry the charge controller chip.

Asus PSUs shouldn’t be hard to find but this might depend where you are.

1 Like

I also don’t know what’s the purpose. On my case it only happens if I charge the CPU fully long enough. It doesn’t brother me. Actually, I never even thought about it before. But now that you question it, you’re absolutely right.

1 Like