@manish_m: Since you are a computer engineer it could be of great worth if you could talk to Lenovo because you are able to confront them with hard facts. 

Another possibility would be to buy a T420s via webshopping and try to reverse engineer the fan controlling software within the 14-day return time.

Should be childs play for you right?

I think we already have made very valid points that Lenovo engineers should consider. And I don't think that reverse engineering the BIOS is really a piece of cake.

Let me get back with a list of questions that I'd like seeing officially answered, @Mark_Lenovo, could you please pass them to the engineering group? Some have already been asked, I'm repeating them since they may be buried many pages ago. Please, could you give feedback on these and not just throw them in the rubbish bin?

1) Could you ask to the engineering why in the world there is such a gap between 2000 RPM and 4000 RPM? It has been shown that the fan is able to run at 3000 RPM, why don't they stick that speed again into the BIOS, letting the laptop using it for the sake of a more quiet life when its not hot (that is, always). A better fan control is certainly possible and definitely needed. I cannot stop stressing how beneficial this would be! Please, ask them what they think of it.

2) Are Windows drivers or the Lenovo power manager software actively controlling the fan behaviour, or they simply reduce the power usage such that the BIOS lowers the fan speed? Said in a different way: is the BIOS the only thing that decides the fan speed, based on power drained by different components, or is Windows helping in setting the fan speed?

3) In the case that the Windows drivers or Lenovo's power manager directly set in some ways the fan speed, why don't you put that control directly into the BIOS (where it belongs), such that every OS benefits from it. Maybe you can add a BIOS option asking if a user wants to sacrifice some performance for the sake of a more quiet behaviour, mimicking the Lenovo's power manager (I think the BIOS already has some power manager options, but they don't seem to produce a noticeable effect)

4) Could you ask the engineering group to try a Linux live CD. It is as easy as to burn one and stick it into the optical drive. I do not know what software they are using on Windows to measure performance, but it will be useful to have an official word about the fan speed on Linux. I'd simply love to here: "we tried, the fan spins fast and we have no means of finding more under Linux, but hey, at least we did boot it!"

5) Can we have a better understanding on how the fan control algorithms work? I understand that it is impossible to leak the complete algorithm, but it would help knowing more about the CPU temperature thresholds used and about other sensors that may greatly impact the fan speeds (just guessing that things such as GPU utilisations and hard drive temperatures have a strong influence). We paid a lot for a laptop where the fan control algorithm mis-behaves, I think knowing some details that might help us solving the problem is a kind of our right.

6) What is the temperature of the testing room where the engineering group works? Is the room icy cold?

7) Why are you testing the laptop only in 20 minutes batches. It doesn't make much sense, since people experience the fan stuck behaviour after hours of use.

8) The laptop runs icy cold and yet the fan goes on like crazy. Why the engineering group did never consider adjusting the thresholds used by the fan control algorithm, such that browsing the web doesn't trigger an increased fan speed?

At the end, I'd love to note how having an open source BIOS will help. I look forward to the day where the BIOS will be available to users putting an end to such kind of issues.

alexcriss: I'm not sure where you're going with questions #2, #3, #4. Many Windows users (like me) are having the same fan control problems. After 4-12 hours of usage, fan gets stuck at 4000RPM while the laptop is ice cold (CPU 35-38C). A quick sleep/wake fixes the problem instantly; the fan speed goes down multiple steps (so this isn't just a case of approaching the threshold from the other direction, as we speculated earlier in the thread.) I have all of Lenovo's power management software installed -- in fact, I'm using the stock Windows 7 installation that came preloaded on the machine.

Reverse-engineering and patching the BIOS isn't a piece of cake, but it has been done in the past -- ironically, to fix a fan noise bug (!) in the T4x that IBM never fixed;

---

wrote:

alexcriss: I'm not sure where you're going with questions #2, #3, #4. Many Windows users (like me) are having the same fan control problems. After 4-12 hours of usage, fan gets stuck at 4000RPM while the laptop is ice cold (CPU 35-38C). A quick sleep/wake fixes the problem instantly; the fan speed goes down multiple steps (so this isn't just a case of approaching the threshold from the other direction, as we speculated earlier in the thread.) I have all of Lenovo's power management software installed -- in fact, I'm using the stock Windows 7 installation that came preloaded on the machine.

 

Reverse-engineering and patching the BIOS isn't a piece of cake, but it has been done in the past -- ironically, to fix a fan noise bug (!) in the T4x that IBM never fixed;

---

I perfectly understand that my questions won't solve the problem, but I'd still love to know more about the behaviour of these machines, as I suspect that there are both bugs and bad software design decisions in their BIOS. Questions 2-4 help pin-pointing the latter. Other questions directly target their testing mode, since that they won't reproduce the fan stuck bug if they do not try harder.

The bottom line is: the fan control algorithm sucks in some ways, please consider changing/improving it to one that does the right thing (tm).

I bought my T420s last May.  I started to make lots of noise about 4 mo. after purchase.  It was a chattering sound.  Also, the fan is always running (though slow), it does make more noise when watching movies. I bought on site warrenty and today the technician replaced the and it seems quiet, though it is still running fast even though I'm not doing much...

Intrestilngly the tech said he has replaced tons of fans on various Lenovo laptops.  I guess there is a difference between IBM thinkpads and Lenovo thinkpads....

@xzhou: many thx for your thinkfan config. 

On Ubuntu Oneric, my system temperature increases up to 56 degree without fan noise. Fan runs around 2000 rpm.

I also install tlp tools to further safe power, and I could decrease power consumption to around 15 - 17 W.

Today, I switched to Ubuntu Precise (beta1 was released yesterday), and also installed thinkfan and tlp tools.

Without any other config change, switching to linux kernel 3.2 decreases system temperature to 46 degree, and also my power consumption decreases to around 10 W. 

One battery charge now provides me with more than 6 hours of power :P

And fan noise using thinkfan is also no longer a problem ;)

I'm happy now.

cu

magic

After seeing this issue in our office with the 2 initial T420s's we received, I held off on purchasing any more. Employees here are fine with their T400s's and T410s's, and while service requests becoming more frequent, I simply cannot updated these laptops as the T420s fan starts to whirl after a 1 second CPU spike while opening any app. It will start to slow down again after 5 - 10 seconds, but that is with the computer sitting idle, basically in a testing scenario. ANY mild activity raising the CPU usage to just 5% will send the fan into annoying noise territory. This is with both power profiles for AC and Battery set to balanced.

I'm sitting here with one of them infront of me now, as the employee who was using it finally snapped and said he refused to work with it any longer, so I've approved a non-Lenovo replacement as the T420s line is basically flawed.

With our time for upgrades soon approaching, and warranties on the T400s models nearing expiration, I'm afraid this looks like the end of the line for Lenovo in our company. I had standardized on them, much to our employees dismay, but I won't be riding this ship to the bottom. At an avg price of ~$2.2k after warranty and accessories, there must be better machines out there, and in a few months I'll have my staff start testing alternatives. If the T430s manages a flawless launch, I'd certainly consider it, but the complete lack of any resolution, and barely any acknowledgement, to this issue over all of this time doesn't leave me with much confidence in the Thinkpad line, or Lenovo's desrire to maintian it.

---

wrote:
Lifted, I saw you mentioned accessories and I was wondering if your t420s uses the Lenovo dock? My issue with the fan running at full blast only seems to happen while using the Lenovo dock which uses the nvidia gpu 100% of the time. The idle temp is up to fifty celcius and any activity pushes the temp into the 60s and 70s. As a result, fan speed is always at 4k.

Does anyone else with t420s and nvidia use the Lenovo dock and have a similar result? Without using the dock the temp and fan speed is decent whether on ac or battery.

---

This does not occur with my T420 Optimus model.

My t420s has a idle temp in the Dock with external Monitor around 45-50°C but at the moment I have no problems with the Fan speet.