ThinkPad T420 Memory Replacement

Introduction

If your Lenovo T420 is running slowly, complaining about memory usage or does not boot up correctly, the problem may be related to a faulty memory module. This guide will show you how to replace both memory modules in your system.

Note: If you need to access the factory memory module, the keyboard has to be removed. Keyboard removal is not required for the bottom module.

Guide notes

Use of a matched pair of memory modules is recommended. Mixing and matching modules works, but may cause system instability. My mixed pair seems to work, but I've had two blue screens and I suspect this isn't the last time it'll happen (errors are not related to memory, but memory is suspect). If you mix and match modules, run Memtest 86+ for ~8 hours and test for stability.
It is important that you do not lose the silver keyboard screw. The RAM door screw also holds the keyboard in, so this isn't the end of the world. However, your keyboard be noticeably loose.

Ce dont vous avez besoin

Étape 1 Unlock the battery

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ThinkPad T420 Memory Replacement, Unlock the battery: étape 1, image 3 de 3

If completing a step like a clone of your old hard drive/SSD, DO NOT remove the battery until the process is complete!
Unlock the latch locking the battery in the laptop.
NOTE: To remove the battery, the tab must be held in to avoid having the lock reinitiate inside the laptop.

Modifier

Étape 2 Release the battery

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ThinkPad T420 Memory Replacement, Release the battery: étape 2, image 2 de 3

ThinkPad T420 Memory Replacement, Release the battery: étape 2, image 3 de 3

After unlocking the battery, remove the battery from the reverse way it is installed to remove it from the laptop.

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Étape 3 Remove the RAM door

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ThinkPad T420 Memory Replacement, Remove the RAM door: étape 3, image 3 de 3

EET owners: Your kit has this bit. No purchase needed.
If you are removing this cover to upgrade/replace your lower RAM module, the keyboard screw DOES NOT need to be removed.
WWAN ready systems ship with antenna covers over these cables. Someone installed a WLAN card in this T420 which disabled the better card and was removed.
Loosen the screw in red (Phillips #2). This screw stays captive in the bottom RAM door cover, and does not need to be removed.
Pull the cover up with a fingernail or a nonmarring pry tool.
Remove the screw retaining the keyboard.

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Étape 4 Remove the keyboard

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ThinkPad T420 Memory Replacement, Remove the keyboard: étape 4, image 3 de 3

Open the laptop.
To remove the keyboard, release the keyboard hooks using a plastic pry tool.
Once the keyboard is loose, remove it from the chassis.

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Étape 5 Disconnect the keyboard

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ThinkPad T420 Memory Replacement, Disconnect the keyboard: étape 5, image 3 de 3

To reinstall the keyboard, refer to the steps in this guide.
This step can be skipped if you remove the keyboard to upgrade/replace the RAM. However, disconnecting it may allow for better access to the upper (Keyboard) RAM module.
If you have a can of compressed air available, some of the dust can be removed at this point. Further disassembly is required for a full cleaning.
Disconnect the keyboard from the motherboard. Use a plastic pry tool for this step.