Hi @xuaks ,
Here’s a list of the supported [https://www.dell.com/support/kbdoc/en-au/000143436/supported-cpu-memory-configurations-on-the-dell-precision-m4600-and-m6600|CPU] in the laptop.
Here’s the [https://downloads.dell.com/manuals/all-products/esuprt_laptop/esuprt_precision_mobile/precision-m6600_owner%27s%20manual_en-us.pdf|owner manual] for the laptop. Go to p.59 to view the necessary pre-requisite steps and then the procedure to remove / replace the CPU