CPU bottleneck when charging - Acer Aspire S 13.

kevsky

My CPU seems to always be limited to 33% when plugging in my laptop to charge but never when it isn't charging. I have already tried resetting my battery, BIOS and the laptop but none seem to fix the issue. I have contacted Acer support but they just suggested to send the laptop to be fixed. Is there anyway to fix it myself?

aphanic

Try to post more details when asking a question like this, we'd at least need to know which laptop you're using, which operating system you have and its version (e.g. Windows 10 1909, you can run winver to check it in Windows).

Now... assuming it's Windows your computer has (and this may very well be a dumb question on my part), which power plan is in effect when the laptop is plugged in? In a recent version you can see it by tapping over the power button in the system tray, otherwise check the Power section of the control panel, for example this is me while connected:



And another suggestion, is it possible for you to try a different charger? Sometimes laptops work in a reduced power state so to speak if they detect the charger to be unable to provide all of the energy it needs. I don't know whether that happens in Acer laptops, but I've seen it before in other brands.

kevsky

Hey, I'm runing Windows 10 version 1903 on the Acer Aspire S 13. I already have it on best performance and trying a different charger won't be possible for me. 

aphanic

If you have a USB stick around we could try something else. There's a little diagnostic environment I compiled based on Windows 10, the idea would be to copy it to the USB stick, boot from it and see if the CPU rises above the 33% when it's being used.

This is the download link: https://mega.nz/#!1N9RiY5Q!L35NhaRmRqeEbknQpnJ95HLxB_yM_z82iwB53bTFuDU

To copy it to a USB stick so that you can boot from it there are several ways, but I think one of the easiest would be to use Rufus. When the utility is opened choose the stick at the top and use the SELECT button with the file you downloaded. It populates the remaining values accordingly (note the highlighted area, it should probably look like that):



Once the copying is finished you can reboot your laptop, and press F12 to select the USB stick from the boot menu. If... there's no boot menu it may be disabled in the machine firmware. When you turn on the laptop press F2 to access the firmware options and enable the boot menu in there

Anyway, when you boot into the drive you should see this more or less (resolution may skew things):



Open Process Hacker (don't worry about its name, it's a task manager) and click on "System information" in the icons blow the menu bar, it should open a screen just like this one but with the details of your machine:



Now move things around, or press Alt+Tab to go to the launcher app (by the way, you'll remain in this testing environment until you close that launcher at which point the laptop will reboot). Open Prime95 and when asked choose to perform just stress testing:



You can leave it on blend in the next screen or switch to one of the two first tests, I don't think it'd matter. Once Prime95 is computing, switch over to the System Information window of Process Hacker and take a look at the CPU usage, see if it reaches 100% (it should):



If it doesn't, and it stays in the 33% just like in your Windows installation, the problem could be either: the charger, the firmware (ensure you have the latest BIOS revision installed in your machine) or some hardware component... and what I can diagnose from here is over I'm afraid, you'd have to get the laptop to a repair shop or Acer support center, etc.

If it does rise above the 33% and reaches 100% for example, then the problem lays somewhere in your Windows installation, which would be the preferrable outcome I guess because formatting the machine and reinstalling Windows (and all of your stuff) anew should fix it; after all that test environment is pretty much a clean Windows 10, there aren't added drivers to the default ones (save Intel's Serial IO and RST).

Anyway, if you wanted to stop Prime, closing it won't do, you have to stop the worker threads:



And to reboot the computer, just close the launcher app .

Just in case you ran into that 33% in there... try switching to the highest power scheme by opening the Command Prompt from that launcher and typing: "powercfg /s 8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c" without quotes. There'll be no confirmation, but you'd have chosen the "High Performance" power plan.

If you end up doing all of this, let us know what came of it ^^,