How to - Lenovo ThinkPad L420 repair, upgrade and update to Windows 10 - YouTube
T420 still a good daily driver but looking to upgrade. Any good options for college/home? : r/thinkpad
T420 Upgrade Options for CPU/Memory - Thinkpads Forum
Lenovo Thinkpad T520 CPU upgrade Core i5 2520M to i7 2760QM - YouTube
Lenovo ThinkPad T420 Review - Itechguides.com
Amazon.com: DBTLAP CPU Cooling Fan for Lenovo ThinkPad T420 T420i 04W0409 04W0627 0B46252 Laptop Fan : Electronics
ThinkPad T420 CPU Upgrade (i5-2540M to i7-2670QM) - YouTube
T420 CPU upgrade to i7 2860QM quad core. Paste is Thermal Grizzly Kryonaut. More info about upgrade and passive cooling upgrade in comments. : r/ thinkpad