T420 - Quad Core CPU and BIOS upgrade (or downgrade)
Posted: Fri Dec 15, 2023 4:49 pm
Hello all 
I still have my old trusty T420 that i love and i don't plan to get rid of it even if for everyday use i have P53.
At the moment i have 1.52 official BIOS installed. I replaced my old CPU with i7-2860QM but it looks like BIOS is allowing me to either have 4 cores or multithreading, not both at the same time (probably due to TPD limitation).
I am not afraid of thermals and i am aware that 45TPD CPU and NVS 4200M is too much for heatsink and fan in T420 but please ignore that here - i am fully aware of issues with overheating.
What can i do to make it run at 4 cores 8 threads? Can i safely downgrade BIOS version to some older, modified version that will allow me to use CPU? Coreboot is unfortunately not an option in my case since it's not supporting Optimus as far as i know.
I still have my old trusty T420 that i love and i don't plan to get rid of it even if for everyday use i have P53.
At the moment i have 1.52 official BIOS installed. I replaced my old CPU with i7-2860QM but it looks like BIOS is allowing me to either have 4 cores or multithreading, not both at the same time (probably due to TPD limitation).
I am not afraid of thermals and i am aware that 45TPD CPU and NVS 4200M is too much for heatsink and fan in T420 but please ignore that here - i am fully aware of issues with overheating.
What can i do to make it run at 4 cores 8 threads? Can i safely downgrade BIOS version to some older, modified version that will allow me to use CPU? Coreboot is unfortunately not an option in my case since it's not supporting Optimus as far as i know.