Surface Pro 4, annoying noise from the back!

Can someone explain why the back of my surface pro 4 (only when the brightness isn't 0% or 100%) makes a noise?

For example, when it is on 25% of brightness it starts making a strange noise slight like a whistling...

Can someone help me?

I have the same issue. I don't understand. Why??

I want to point out that I started a separate thread about the modem-like screeching noise which may be related to c-state but which is not related to brightness level like this thread is. Someone has since merged my thread into this one but they are not the same issue!!!! VERY CONFUSING AND WRONG

Hello GiovanniSm

When did this start happening?

Can you confirm that Surface is fully up to date?  Did all updates install successfully?

Do you notice this happening under other circumstances, beyond dimmed screen?

Best regards

My SP4 M3 model has the same. Funny... if you start a watch panel (where you adjust time).. the noise will be modulated every second, every time second arrow is moved in the analogical watch on the screen. Definitely it has something to do with changes in the screen.. pen, content changes..

Well, I've done some digging and it seems this noise was reported way back on the first Surface Pro. It appears to be to do with when the CPU enters various c-states (when idle).

There is a thread here about it.

One of posts suggests the following workaround, essentially disabling the idle state:

You can disable the ACPI C2-state and C3-state by setting a registry key. To do this, follow these steps:

1. At a command prompt, run the following command:

reg add HKLM\System\CurrentControlSet\Control\Processor /v Capabilities /t REG_DWORD /d 0x0007e066

2. Restart the computer.

Note The computer idle power consumption will increase significantly if the deeper ACPI C-states (processor idle sleep states) are disabled.

To continue to benefit from these energy-saving states, remove the registry key that you set in step 1 after you install the hotfix that this article describes. To do remove the registry key, follow these steps:

1. At a command prompt, run the following command:

reg delete HKLM\System\CurrentControlSet\Control\Processor /v Capabilities /f

2. Restart the computer.

I have found this improves the noise a lot but the question of course is what adverse impact this will have on battery use or heat etc. Time will tell I suppose.

It's pretty annoying that this has been known about for this long and Microsoft/Intel have not addressed the problem properly.

So I'd like to know for sure one way or the other whether other Surface Pro 4 users can hear this noise from the back of their device (easiest to hear from the vents at the top near camera).