UEFI alongside CSM, independent of CSM
UEFI alongside CSM, independent of CSM
Your HP Elitebook 8470p runs on Legacy BIOS and UEFI, but the system displays options like "UEFI with CSM" versus "UEFI without CSM." The difference lies in whether the chipset supports Compatibility Mode Support (CSM). CSM enables better compatibility with older hardware and drivers, especially for legacy devices. If you need full support for older software or hardware, choose "UEFI without CSM." If you want improved performance and newer features, "UEFI with CSM" is recommended.
It extends beyond that but for a brief summary yes, this. In short, CSM enables devices built for BIOS to function in UEFI environments. A clear case is GPUs—those made before around 2012 won’t support UEFI output, so the UEFI BIOS must run with CSM enabled to make it work. On your laptop, there’s no need to turn on CSM.
Without the CSM, performance is better in my laptop case. However, based on the specs you provided, it has an AMD Radeon HD 7570m with 1GB of RAM and a 256GB SSD plus a 500GB HDD.