ThinkPad T420 BIOS Mod with downgrade support for 1.48+
The ThinkPad T420 and other xx20 laptops have long suffered from a crippling bug that causes 100% CPU usage when an eGPU and 16GB of RAM are installed simultaneously. This most likely stems from a lack of support in BIOS for 1600 and 1866 MHz memory modules. Lenovo has never bothered to release a patch, but Oleh and later BDMaster from BIOS-Mods released a custom BIOS fixing the issue. For ease of access, I've uploaded his BIOS here, along with a nicer BIOS logo and a method to downgrade from versions 1.48 and 1.49.
- Based on v1.46
- WLAN whitelist removed - can use any wireless card
- 1600MHz & 1866MHz RAM support
- 16GB RAM Support, stable with an eGPU
- Lots of extra menus available for additional configuration
- Updated splash logo included
- Can downgrade from 1.48 or 1.49 by using winflash's
This software can and may turn your computer into an unusable brick. I didn't write this software, and I offer no support, guarantee, or warranty in relation to this product.
t420-bios-sdx1.zip - For T420 and T420i ONLY, v1.46, 8.22MB
- Plug in your ThinkPad. Make sure it's fully charged.
- Unzip the archive.
- Run "Downgrade from 1.48 or later.cmd". Follow the on-screen instructions.
- (Optional--to get the new logo) After restarting, run WINUPTP.EXE from the same folder and follow instructions. Click yes when prompted about the startup image and the older version.