T420s: noise and heat

[mikemex]

I'd like to open a thread to report results from my ongoing research on the topic of T420s heat and noise.

I'll begin by saying that, so far, I've not found anything abnormal about the T420s compared to the X220 or T420 (which I also own). It reaches nearly 100°C under load; but so does the T420 and X220 if you leave them running long enough. What is different in the T420s, is that temperature changes very abruptly; it's more stable on the X220 and much more stable on the T420. I still don't understand why,

What've concluded is that T420s can be configured to work cool and stay reasonably quiet with minimal effort. You just requiere TPFanControl and some tinkering with the BIOS, Windows and browser settings.

First, TPFanControl:

Editing the .ini file, I've been experimenting with different thresholds and so far, I've determined that this table of values works very well:

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Level=40 0
Level=43 1
Level=46 2
Level=49 3
Level=52 4
Level=55 5
Level=58 6
Level=62 7

It's purpose is to react quickly to temperature raise and engage full speed much earlier.

BIOS:

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Disable the discrete graphics card entirely by selecting integrated graphics.

I don't even understand why Lenovo decided to put discrete graphics on the T420s. It runs incredibly hot if you select "discrete graphics".

Windows:

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Disable Turbo by selecting a maximum frequency of 99% in the CPU governor under energy profile.

In my case (2640m), the top frequency becomes 2.8 GHz, instead of 3.3/3.5 GHz.

Browser:

If you use Firefox, install:

Code: Select all

NoScript to block unwanted scripts and enable them temporarily as needed.
Don't enable them permanently or you'll end up enabling everything and the protection will be gone.
It takes some guessing to decide what to enable, but often stuff with 'cdn' related to the site you're visiting will be
enough. And, of course, the main site itself.

h264iy. Not entirely necessary, but forcing hardware acceleration on videos unloads the CPU and it's been a great strategy
on my X301 to both reduce the temperature and extend the battery life.

With clean heatsink fins,and a clean Windows installation (minimal bloatware with under 5% of usage on idle at 800 Mhz) I get:

* Idle temperature of of 44 °C.
* Temperature during regular web browsing of between 46 and 50 °C, with minimal fan noise (most of the time it runs at 1967 rpm).
* Temperature under 1080p60 youtube video: 58°C with about 40% usage at 2.8 GHz.
* Temperature during stress test with 7-zip benchmark: 72°C.

[Sweater Fish Deluxe]

I don't even understand why Lenovo decided to put discrete graphics on the T420s. It runs incredibly hot if you select "discrete graphics".

The Nvidia GPU was certified for use with CAD and 3D rendering programs, but the integrated graphics on the CPU were not. So it was useful for some corporate buyers at the time.

The issue with disabling the discrete GPU in the BIOS is that you lose the DisplayPort output. Luckily, I don't think there's any difference in temps or power use between Optimus graphics when the Nvidia GPU isn't being used and having the Nvidia graphics totally disabled in the BIOS. At least I've never been able to see any.

[mikemex]

The Nvidia GPU was certified for use with CAD and 3D rendering programs, but the integrated graphics on the CPU were not. So it was useful for some corporate buyers at the time.

The issue with disabling the discrete GPU in the BIOS is that you lose the DisplayPort output. Luckily, I don't think there's any difference in temps or power use between Optimus graphics when the Nvidia GPU isn't being used and having the Nvidia graphics totally disabled in the BIOS. At least I've never been able to see any.

Thanks for the heads up. I've been experimenting and indeed, disabling the nVidia GPU under WIndows is just as effective as disabling it in the BIOS. I'll edit the guide to reflect your suggestion.