T420 Thermal Paste Issue/Replacement Tutorial

Discussion in 'Lenovo' started by iCrazyNoob, Jul 9, 2012.

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  1. iCrazyNoob

    iCrazyNoob Notebook Guru

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    Hi everyone, I purchased my T420 about a year ago, and did some stress testing when I got it. The temperature was at a stunning 96C with prime 95 running. I thought of it as a cooling design flaw and left it for about half a year idling around 60C and heavy load around 85-90C.

    If you have some similar temp under stress, then please think about replacing your laptop's thermal paste because they are very badly applied and probably some really cheap paste.

    In my case there was way too much paste in between creating a heat barrier therefore causing such a high temperature inside the CPU. After all the work, my laptop runs happy idle around 45C and full prime 95 load @ 80C MAX never reached over 80C. Room temp is around 26C.

    =========================================================

    Here's the step by step tutorial on How to replace your thermal paste:

    What you will need:
    -New Thermal Paste, Preferably Arctic Silver 5, It's about 10 dollars where I got mine.
    -Slim Phillips Screw Driver, some screws are pretty deep, a thick shaft cannot reach in <.<
    -A place to put all the screws

    Optional:
    -A small flat head screw driver to pry out keyboard connector and touch pad connector if you can't reach by hand. Also the keyboard bezel needs to be pried as well.

    [​IMG]

    Step 1:
    Turn off the laptop, Remove Battery, Take off the memory service panel.


    [​IMG]

    Step 2:
    Take off the Keyboard assembly Screw


    [​IMG]

    Step 3:
    Remove Keyboard by pushing it towards LCD and lift at bottom. Carefully pry the keyboard connector. DO NOT PULL on ribbon cable!


    [​IMG]

    Step 4:
    After removing the keyboard, close the Screen and turn laptop upside down to remove bezel screws. Total of 5 under the laptop. Note #2 screw is a tiny one, all 4 others are long ones.


    [​IMG]

    Step 5:
    Turn laptop over and remove more screws under keyboard that holds the bezel.


    [​IMG]

    Step 6:
    This is the tricky part, the bezel is held in with little hooks all around and u need lightly pry it open starting from the front, reach in with a flat head from bottom and lightly pry all the little hooks open, then move to the left side, and then right side.
    Careful around the headphone jack, it seems really hard to open the hooks around it so i basically left it and after all others are loose it will be loose and easy to take out.

    Location of all the hooks:


    [​IMG]
    [​IMG]

    After bezel is removed:

    [​IMG]

    Step 7:
    Remove the left speaker unit above the fan heatsink.


    [​IMG]

    Step 8:
    Unhook the cable from the heatsink


    [​IMG]

    Step 9:
    Unscrew the heatsink bolts and GPU clamp


    [​IMG]

    Step 10:
    Unplug the fan connector.
    Lift up the heatsink at an angle and slightly pull it out towards you.


    [​IMG]

    [​IMG]

    [The paste you see in my picture is not the stock paste. I have applied Arctic silver once but had my motherboard replaced recently therefore I'm redoing the paste fresh.]

    [​IMG]

    Step 11:
    Clean the GPU, CPU, and both heatsinks. I just used dry paper towel since my house didn't have anything else. It works OK in my opinion.


    [​IMG]
    [​IMG]

    Step 12:
    Apply new thermal paste, In the picture I put too much as pointed out! all you need is a pea sized dot on both GPU and CPU!.


    [​IMG]

    Step 13:
    Carefully put the heatsink back at an angle and put it down on top of the CPU+GPU, screw in the CPU heatsink according to the number printed on the heatsink. (Cross Pattern). Apply some pressure in a round motion on the heatsink after all the bolts are tight, this to ensure all the air in between gets pushed out.

    *DONT FORGET TO RECONNECT THE FAN CONNECTOR!*


    [​IMG]

    Step 14:
    I bent my GPU clamp a bit more to get the max pressure, but don't bend too much or you might break it.


    [​IMG]

    Step 15: Push down on the GPU heatsink and apply pressure, without releasing the pressure applied with ur hand, put the clamp in position and tighten it.

    [​IMG]

    Step 16:
    You should be good to go! From here on is the reassembly tut if you cant remember.


    Step 17:
    Hook the LCD cables back in the heatsink.


    [​IMG]

    Step 18:
    Screw in the Left Speaker.


    Step 19:
    Hold bezel at an angle so you can reconnect the touchpad connector, might take a few try but you will get it in. DO NOT use excessive force.


    [​IMG]


    Step 20:
    Slide the front of bezel under the LCD at an angle, Make sure you apply some pressure near middle because the hooks wont hook with no pressure.


    [​IMG]
    [​IMG]

    Step 21:
    Push the bezel down after the front is all under the LCD and properly hooked.
    Careful at the headphone jack again.


    [​IMG]

    Step 22:
    Screw in the 3 screw from the top and 5 screw from the bottom that holds the bezel in.


    Step 23:
    Push in the keyboard connector, should not require much force at all, lining it up is the main point.

    [​IMG]

    Step 24:
    Put keyboard in at an angle, then pull towards you.


    [​IMG]

    [​IMG]

    Step 25:
    Turn laptop over, screw in the keyboard screw, and close up the memory service panel with the screw.


    Step 26:
    Put Battery back in!


    =========================================================

    Heres some result after the thermal paste change! It's probably nor the best result, last time I did the temperature was around 70C Max seems like I probably put a bit too much or just unevenly spread. Or simply cuz I last did my change in winter and now its summer with higher room temp..

    [​IMG]

    Hope this helps people that had trouble changing their T420's thermal paste! It's my first thread to help others after getting so much help from you guys! Thanks for reading. :D
     
    Last edited by a moderator: May 8, 2015
  2. PatchySan

    PatchySan Om Noms Kit Kat

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    Thanks for the good guide, I will sticky this on the T420 page for future reference. Adding copper shims under the heatsink could be worth considering as it worked nicely for me, my idle temps is around 39-41c while under load it reaches 71c.
     
  3. m0biusace

    m0biusace Notebook Enthusiast

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    Is there a reason why you put a dot on the GPU, and a line on the CPU? I'm thinking of repasting a laptop when I get it in my hands later this week and im wondering which is the best to do.
     
  4. mochaultimate

    mochaultimate Notebook Consultant

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    This is a great guide and certainly deserves a sticky. Thanks!
     
  5. iCrazyNoob

    iCrazyNoob Notebook Guru

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    Because the GPU is square and has way less surface area than the CPU, so a dot is enough to cover the whole thing. On the other hand, the CPU is rectangle and has larger surface area, so a dot is gonna be harder to get even separation.
     
  6. c17chief

    c17chief Notebook Consultant

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    You used WAY to much AS5. It looked like it in the first removal pics, and I see why on the application pics. You only needed about half what you used. Less is more when it comes to that stuff. Glad it helped since your temps were def hot before, and they are a lot better now, but next time you have to tear into it or do up another machine, don't use so much! Your temps may even be better still if you dont.
     
  7. iCrazyNoob

    iCrazyNoob Notebook Guru

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    kk thx for the heads up, that was my second time so I don't know exactly how much to put on there. there's way to many theory on the internet with lines dots etc.
     
    sadegh62 likes this.
  8. turqoisegirl08

    turqoisegirl08 Notebook Evangelist

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    @Sadegh62. Did you have to put all of that in a 'Reply With Quote?' You did not even ask a question as well...just copy-and-pasted a post from another forum member:confused:
     
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  9. mattpickus

    mattpickus Newbie

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    Nicely done example, but a few notes:

    1. Not all T420 models have a GPU. If you have one of those you only need worry about replacing the thermal compound on the CPU, and it should be obvious from the shape of the heat sink whether there is a separate GPU or not.

    2. On mine there were a few connectors underneath the bezel. When you lift the bezel from the front, make sure you do not damage the connector that is right below the touch pad, and when you replace everything make sure the connector is firmly seated before reassembly. The connector on mine was in the MIDDLE of the ribbon cable, and Lenovo thoughtfully left enough slack in the cable so that you can get a fingertip on the top of the connector when reassembling everything.

    3. On the underside of the bezel, immediately adjacent to and on either side of the touchpad, are several other ribbon cables with connectors. When lifting the bezel off, the connector for my Bluetooth card came loose (this was to the left of the touchpad, near where the Z, X, and C keys would be if the keyboard was installed). It is simple to fix, just reseat the connector similar to the connectors for the touchpad and keyboard. However, if you forget to do it you will have no Bluetooth when you power up and will have to dismantle the computer back to the "remove bezel" step to access it. :eek: The same applies to the touchpad if you forget to reseat that connector.

    Overall, as laptops go this is one of the easier machines I have worked on. Getting the bezel loose is the most difficult part, the rest is just screws and snap connectors. Take your time with the bezel, work to loosen the left and front sides first and it will be easier to get the right front corner loose because you need some extra wiggle room to clear the headphone jack. Once the bezel is free of the headphone jack, the rest is easy. Just remember the touchpad connector!
     
  10. Romanpsh

    Romanpsh Newbie

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    Hi! Awesome guide and amazing results! Just replaced thermal grease for my T420 (I used Arctic MX-2). Results are stunning, before that I tried cooling pads, but the breeze they produced never reached or affected the core temperatures, it just cooled the plastic bottom, that's all they did.
    I had similar temperatures when stress-testing with prime, max temperature ~ 96 at max load and around 40 when idle. After thermal grease replacement biggest difference in temperature is under max load, so far, with prime stress testing and writing this post (10-15 min) max temperature is 78 degrees, at idle it dropped down to 33, but I think 35- 40 is more realistic after laptop warm up.
    Anyway, that's a must to do if you care about your laptop life, it reduces max temperature by at least 16 degrees in my case, that's a very big change!
    Thanks for thorough guide mate, without it I wouldn't dare to disassemble my Thinkpad. Turns out it was easy and super effective!
     
    Last edited: Feb 26, 2015
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