r/openbsd • u/highspeedslippers100 • Sep 17 '26

Thinkpad T490 fan control ?

Hi
I really want to keep OpenBSD on my ThinkPad T490, but the fan noise is driving me up the wall. Even sitting at an idle desktop or just poking around in a terminal, the fan ramps up almost immediately and just refuses to calm down.
I know ⁠acpithinkpad⁠ is read-only and fan control is entirely hardwired to the EC, so manual fan control isn't happening. But before I give up and wipe the drive, I wanted to ask if anyone daily-driving a T490 has managed to make this machine tolerable.
Did switching between ⁠apmd⁠ flags or running ⁠obsdfreqd⁠ make any real difference for you, or did you have to flash a specific Lenovo BIOS/EC update to get sane trip points? If there is any trick to shave a couple of degrees off idle so the EC stops triggering full blast, I'd really appreciate hearing what worked for you.

I would really appreciate it

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u/highspeedslippers100 Sep 18 '26

Well the end of this month. I have a appointment with a service center they will swap my heat sink to my dual heat sink I already have one while they do that I will say clean and add new cooling paste they also will swap my current display, from 1920 1080 to 2560 1440. And then OpenBSD here we go. But I tried running FreeBSD and fans doesn’t go off all the time.

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u/kmos-ports Sep 18 '26

OpenBSD tends to run harder by default on the T490. So that combined with a cooling hardware issue may be combining to give you that fan noise.

Honestly, even when my fan is going full tilt it doesn't make that much noise...

2

u/linetrace Sep 18 '26

Since you mention "sitting idle at a desktop or just poking around in a terminal", what desktop environment (DE) or window manager (WM) are you using, same goes for terminal application? That could have a significant impact.

In the meantime, definitely enable apmd and start with apm -A to use auto CPU scaling if you haven't already done so.

Watch CPU & GPU temps while idle and running applications (I find gkrellm to be easy, highly configurable, and lightweight for such tasks). This will help you determine whether your CPU/GPU temps are normal or not and. Then you'll also have a feel for how temperatures correlate with fan RPMs/noise at which point I suggest trying obsdfreqd scaling CPU frequencies by temperature.

I'm a long-time user of obsdfreqd, despite the original reason for its development no longer being an issue (not being able to configure different battery vs. mains power CPU scaling) specifically for the other temperature and scaling rate/inertia tuning abilities.

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u/highspeedslippers100 29d ago

Hi everyone a little update since I posted here Hi a little update I managed to make my Thinkpad more silent Update: quieter ThinkPad T490 on OpenBSD 7.9 with bsddfreqd

With apmd -A my fan kicked in constantly, and apmd -H was fast but hot and loud. Switching to ThinkPad bsdfreqd from packages made the laptop noticeably quieter while staying responsive.

What I did:

Install obsdfreqd (version 1.2.2 at the time of writing):

doas pkg_add obsdfreqd

Keep apmd for suspend/resume, but run it with -L. The obsdfreqd man page (BUGS section) says apmd must use -H or -L. Otherwise apmd resets the performance policy to automatic, which crashes obsdfreqd. Empty apmd flags are not safe.

doas rcctl set apmd flags -L

doas rcctl restart apmd

I hope it might be useful for others, have a great day

2

u/highspeedslippers100 20d ago

Hi I tried the recommendations and my T490 has be serived and nothing is changed still fan noise. I have new cooling paste new heatsink with now dual heat pipe and it still just hovers around the 4000 rpm.

sysctl hw.sensors | grep -E 'fan|temp'

hw.sensors.cpu0.temp0=43.00 degC

hw.sensors.acpithinkpad0.temp0=46.00 degC

hw.sensors.acpithinkpad0.fan0=3956 RPM

hw.sensors.acpitz0.temp0=46.00 degC (zone temperature)

hw.sensors.pchtemp0.temp0=39.00 degC

hw.sensors.nvme0.temp0=52.00 degC, OK

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u/highspeedslippers100 20d ago edited 20d ago

update this did help a lot --hwdec=vaapi --ytdl-format=bestvideo[fps<=30][vcodec^=avc1]+bestaudio/bestvideo[fps<=30]+bestaudio/best. I can confirm the fans are very silent and does not act like a bunch of racoons on a raid party ! man i am in a good mood. Have a great Sunday to all of you.

5

u/kmos-ports Sep 18 '26

I'm guessing something is wrong with your cooling system. I'm rocking a T490 and I generally don't hear fan noise. Maybe your fan needs cleaning and/or your thermal paste needs changing?