5-10 years ago the answer was…yes to the first question as the second one didn’t apply. As I have been watching the evolution of hardware over the years things of course are more complex. In a nutshell going with a low power server(or maybe a desktop CPU for workstation users) actually harms performance more than any increased power. In fact with the newest CPU’s from Intel(AMD is a bit behind) running Windows in the “Balanced” power profile actually HURTS both power savings and significantly inhibits overall performance. One the desktop the roles are a bit reversed…the absolute power savings most likely would be worth the performance hit IF you aren’t worried about complex, real world tasks(like real time rendering, financial analysis..etc etc etc)).
Power Management: Can Windows Mange power better now? Are new low power CPUs better?