When will it be necessary for the system administrator to perform a OS upgrade?

A.
Installing a compatible Hard drive

B.
Installing a compatible RAID controller

C.
Installing a compatible processor

D.
Install Windows then adding a additional processor

Explanation:
If you are going to add additional processors to the server board then your operating system will also require upgrading to support multiple processors.
Incorrect
Answers:
A: This would be detected and would have been put in use already and does not require a BIOS upgrade.
B: This would be detected and would have been put in use already and does not require a BIOS upgrade.
C: This would be detected and would have been put in use already and does not require a BIOS upgrade.
Reference:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 380.