The T420 can achieve near 200MB/sec read speeds with USB 3.0 via Expresscard, despite some power limitations with external HDDs.

The T420 lacks HDMI but includes a mini DisplayPort, which can be adapted to HDMI or DisplayPort for external display connectivity.

Disabling TurboBoost and security updates using InSpectre can lead to lower operating temperatures and improved performance on Windows 10.

Replacing the thermal paste with Arctic MX-4 can help manage heat issues on the T420s, especially when running Windows 10.

A display upgrade to a 300 nits 1080p IPS panel is possible, significantly enhancing visual clarity and brightness over the original screen.

Owners recommend upgrading to an SSD and increasing RAM to 8GB or 16GB for significant performance improvement in boot times and responsiveness.

Flashing the BIOS with Coreboot allows the T420 to support Ivy Bridge CPUs, enhancing integrated graphics alongside CPU performance.

Upgrading the CPU to a Quad Core i7, such as the i7-2820QM, is feasible and can enhance the laptop's capabilities for more demanding tasks.

Windows 10 Enterprise 2016 LTSB is recommended for older ThinkPads due to its lighter footprint and longer support, performing better than standard Windows 10.

Windows 10 LTSC 2021 runs well on the T420s, but some users note that Fn+F1~F12 key combinations may not function properly.

Users find that Linux distributions like Mint or Debian work well on the T420, offering better performance than ChromeOS Flex.

The T460s offers a better screen and battery life compared to the T420s, though the T420s is praised for its superior build and keyboard quality.

The T420 is capable of running Ableton smoothly, suggesting adequate performance for music production tasks despite its age.

The ThinkLight feature is highly appreciated for night-time use, enhancing the T420's usability in low-light environments.

Replacement of the T420 keyboard is quick, taking about 5 minutes; new keyboards can be sourced from surplus inventory or platforms like AliExpress.

Swapping RAM and CPU on the T420 is described as a straightforward 15-20 minute task due to its accessible design.

Replacement batteries for the T420 are available for under $50 on platforms like AliExpress, making it an affordable upgrade to extend usability.