Fix a Thinkpad T400's Thermal Issues Once and for All




About: Leander is a graduate of several challenging technical programs including the Northeastern University College of Computer Science, the Legend of Zelda, and the Marathon series. He has previously worked on ev...
Thinkpads are great machines. Reliable, repairable, fast, and the best keyboards you'll find on a laptop.

But until recently, they've had one terribly fatal flaw: they overheat if you do anything even slightly demanding on them. My personal machine is a Thinkpad T400. It plays a mean game of Minecraft, and this is the story of what happened the day it overheated and shut down while I was fighting a creeper near some lava.

Tools and materials:
  • Small philips head screwdriver with a longish neck
  • Power drill
  • 3/8" or so drill bit (spade or twist, doesn't matter)
  • Can of compressed air
  • Thermal grease
  • Exacto or utility knife
  • Sturdy, fine-apeture screen such as that from a "gold" coffee filter
  • Superglue or expoy
  • (optional) Sandpaper wrapped around a dowel

Step 1: RTFM

To get started, go to Lenovo's support site and download the hardware maintenance manual:

Flip to page 110, "Fan Assembly" under "Removing and Replacing FRUs", and follow the directions there. It will tell you what you need to disassemble first and step you through it with far better diagrams than I could ever draw. Don't panic at the apparent complexity - there are a lot of steps, but the whole thing comes apart logically and simply. This laptop, unlike most, is designed to be worked on.

When you've got the heatsink/fan unit removed, go on to the next step.

Step 2: Dust Is the Devil

With the heatsink/fan removed, attack the whole business with a can of compressed air. In particular, blow air into the case vents under where the fan sits, under the metal plate beneath the fan (which hides more vents underneath itself), and aim some underneath the motherboard. In general, you want to blow air in the opposite direction the fan usually pushes it. This is particularly important for the case because there are filter screens in the vents that accumulate a ton of dust, and blowing with the normal airflow will just pack it in tighter.

To clean the heatsink, hold the fan still with a finger (if you don't, the airflow may drive it past it's maximum RPM, leading to premature failure) and blow compressed air into the heatsink's fins where the hot air normally comes out. Again, you're trying to blow opposite the airflow in order to dislodge the most dust.

During this process, be careful of the heatsink surfaces - to extract heat effectively, the parts of the heatsink assembly that contact the chips on your motherboard have to be flat and perfectly parallel to each other, and the heatsink is made of soft copper that can bend or scratch pretty easily. Mostly, don't just lay it "face down" on your bench and you'll be okay (anyway, doing that will get thermal grease all over your work surface).

Step 3: Piercings Make You Cooler

This step is optional, but in my opinion very worth doing. There is a bit of a trade-off in that you're sacrificing a bit of the spill-resistance Lenovo have designed into the machine by opening up holes on the bottom of the case that lead directly to the interior - normally, the intake holes underneath the laptop lead air on a convoluted course that will prevent coffee spills or whatever from being sucked up by the fan or generally getting inside the machine, but it's this convolutedness that contributes to the overheating problems in the first place.

I took this trade-off because I almost never use the machine on a surface that could convey that type of spill, but your mileage may vary.

If you're going to go ahead with the surgery, take a good look at the way the fan sits in it's place when it's installed, and take note of what part of the case directly covers the "face" of the fan. Put the heatsink aside, take up your drill, and drill a series of holes in the plastic casing so that you'll be able to see fan from outside the case once everything's back together. Basically you're trying to make as wide and direct a path for air into the fan as possible.

Make sure to space the holes out enough that you don't weaken the case excessively - this is a high-stress area and a case failure here would probably destroy the fan.

Once you've drilled the holes, you'll probably want to smooth their edges. I found that some self-adhesive sandpaper wrapped around an appropriately-sized dowel was the perfect tool for the job and yields a finish that would be indistinguishable from factory stock if I'd only bothered to drill the holes on a regular grid.

Step 4: Add Coffee and Fire

Yes, I found a way to involve a blowtorch in the project.

Now that you've made giant holes in the bottom of your computer right over one it's more mechanically vulnerable parts, you need to protect the insides somehow. In this case, the big threats are dirt and random stabby things (like your finger picking up the computer).

My solution is to cover the holes from the inside with a heavy screen with a very fine mesh: a "gold" coffee filter (they're not really gold, as we'll see). You want something good and stout, it will be standing up to a fair bit of abuse.

If you're lucky, the one you have has an uninterrupted area of mesh large enough to cover the holes. I wasn't lucky, which meant fire: usually, these filters are made by forming the mesh into a filter-shape and then molding plastic supports directly over the mesh, which has a much higher melting point than the plastic.

With me? This means you can reverse that process with nothing but a blowtorch and a very (VERY) well-ventilated area. In the process, you'll find that the golden coating burns away, too, leaving the mesh a charcoal color that about matches ThinkPad-case black.

Step 5: Glue the Screen Down

Once you've obtained your filter screen, cut it to shape and glue it down over the vent holes you drilled. Make sure you glue the edges securely and all the way around each hole so the screen won't pull up under stress.

I used superglue to attach the screen because I'm impatient, but I'd really recommend something thicker like epoxy. I had a terrible time with the glue wicking through the screen and blocking up the air holes by filling in the screen's holes.

Also, be very careful to make sure the metal screen can't come loose and short out the nearby motherboard. The CPU is right there, so a short in this area would probably destroy lots of important and expensive things.

When all the surgery is done and the glue is dry, have at the whole thing with compressed air again to get rid of any debris you created.

[There was an image for this step, but it died in a tragic alpha testing accident. All part of bringing you a better Instructables experience!]

Step 6: A Little Grease Never Hurt Anyone

Now you need to redo the thermal grease on your CPU and GPU. Follow steps 6 and 7 of this excellent Instructable:

You may wish to use a little less thermal grease than he does. As he says, too much is actually counterproductive.

Note that one of the chips serviced by the heatsink (the northbridge) has a thermal pad instead of thermal grease - don't try to clean away the pad! There's not much you can do with it but make sure it's seated precisely when you go to re-install the heatsink.

Step 7: Heat Sunk

Now it's time to reinstall the heaksink. Seat it in place, but before you anchor it down with the retainer place, wiggle it around side-to-side somewhat to make sure the thermal grease is spread out well. Don't press too hard while doing this or you'll scratch the heatsink surface or damage the chips.

Also, before you install the anchor plate, bend the tab shown in the picture downward a bit to make sure there's enough pressure holding the GPU portion of the heatsink in place (this little tab is the only thing keeping the heatsink attached to the GPU and it can bend back over time).

Once that's done, reverse the instructions in the maintenance manual to put everything back together, and fire the machine up.

If you're obsssive like me, you'll notice that your fan is running a few hundred RPM slower at full tilt than it did before. This means you've succeeded: it's more loaded down because it has more air available to move. Your vacuum cleaner speeds up when you plug it's hose for the same reason - it can't get any air to move, so it spins a lot faster.

Step 8: Grognards and Neckbeards Only Beyond This Point

Windows users are done now and can optionally investigate fan control tweaks for that platform.

Linux users should install Thinkfan: . You need at least version 0.8.1. If you're using Ubuntu 12.10, it's in the package repository as just "thinkfan", and if you're running Arch it's available in the AUR.

What you also need is to configure it correctly (the default config is no better than just letting the BIOS run your fan). My thinkfan.conf is attached to this step. I have extremely aggressive temperature thresholds set because I don't mind fan noise, but it should be a good basis for your tweaking. Download it to /etc/thinkfan.conf to use it. You'll also need to make sure that thinkfan runs in "dangerous" mode, a configuration change which differs for each Linux distribution. You can figure out how to make the change by looking at thinkfan's manual, and looking up how to edit startup scripts (init.d, initrc, systemd, or upstart, depending) on your distro.

All that said, the really important thing about my thinkfan.conf is the fact that in addition to reading temperature from the ibm-acpi sensor group, it reads "ACPI Thermal Zone 0" (or acpitz0 on some machines), which for the T400 is a temperature sensor mounted actually on the CPU silicon, rather than nearby on the motherboard as with the other. If you watch this sensor with one of the various graph-generating tools, you'll notice it changes really quickly, almost 1:1 with processor load. It's also the sensor that triggers an emergency shutdown when it reaches 100C, so it's the one you want your fan to worry about. This does have the side effect that your fan will change speed a lot more often than using the other sensors, but it's worthwhile to end the overheating once and for all.



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12 Discussions


3 years ago

This mod is very useful and it really breathed new life into my t400. However, i can't seem to find the thinkfan.conf attached to this post. I bet i could probably make my own but, i don't mid fan noise either so the faster the fans are running the better i feel that it is doing its job.

1 reply

Reply 3 years ago

You couldn't find the conf, because...I never attached it to the instructable! I've finally after all these years fixed that, you'll find it as an attachment on the last step.

Rick Camper

3 years ago on Step 8

Nice writeup...will be buying 2 of these for needed Winblows machines. Thanx !


4 years ago on Introduction

Hi There, I'm having this problem and I'm going to do the cleaning first. Because it was nevery too bad really. I was actually wondering if a cooling tray will help the laptop? Considering that it's a problem with ventilation and that every time the table feels really hot. So I'm thinking if the surface it's on can absorb more heat it can resolve the cooling issues. Any comments on this as a solution?


4 years ago on Introduction

So I thought I followed this successfully and put everything back together again. We were able to boot & login once and then it blue screened, and now it won't boot. Get the option to start Launch Repair, which does some repair and then shuts down. If we go the Start Windows Normally route, it blue screens before getting to the login screen. Did I not plugin in something properly?

1 reply

Reply 4 years ago on Introduction

I opened it up again and made sure all the connections were good (they were) and then left out one of the keyboard screws smack in the middle on the bottom because it seemed to have too much resistance. It booted, fingers crossed.


5 years ago on Introduction

Done. I'm not sure if it helped though. I'm still seeing temperatures up to 80 degrees while compiling stuff. It hasn't shut down for me yet, but still seems to hot. Maybe I didn't use enough thermal grease. How high of temperatures are you seeing?

4 replies

Reply 4 years ago on Introduction

Is that 80 celsius or Farenheit? My T400 routinely shuts itself down nowadays and I'm barely doing anything. I suspect heating issues and I'm going to replace the heatsink/fan assembly AND considering this mod.

You actually need deceptively little thermal grease - less than 1mm^2 or so.

80 degrees sounds about right when doing anything heavy, especially if you haven't messed with your fan control settings - even with the mod the heatsink and fan on this machine are only barely adequate. I routinely get over 90 even with this mod, but I can at least compile webkit without an emergency shutdown.

Great, thanks! That sounds like about the amount of grease I used. I was hitting 80 degrees while compiling FreeCAD, which would previously require putting the laptop in the refrigerator to avoid shutdown ;-)


6 years ago

You seem to like fire a lot...