Can I do in-place cpu and memory (hardware) upgrade while rhel OS is already install ? Will if affect installed OS ?

Issue

• We are planning to upgrade our database servers, due to some CPU Utilization related issues.
• For example,
  the present Hardware details of the system are:

Server : HP DL 580 G5
Processors : 2*Dual core
Ram : 32 GB
Disk Size : 300*2
Raid Level : 1+0

The up gradation is with respect to processor and RAM and the upgraded configuration would be:

Processors : 2*Quard Core
Ram : 64 GB

• Can I do in-place cpu and memory (hardware) upgrade while rhel OS is already install ? Will if affect installed OS ? Will it affect installed applications ?