Like most IT Professionals I've built my own machine and overclocked/undervolted machines. When making changes like this it's important to get good monitoring software. Even as a DBA it's important to have a good understanding of the hardware your database instances are running on. The tools below are not only great, they're free!
I am fortunate enough to own a laptop that I can replace the processor on, and after unscrewing about a million screws, I updated the processor. Unfortunately the fan and heat sink is not adequate, so I've spent several weeks trying to under-clock and under volt my CPU. Core Temp enabled me to monitor the heat of my processor, and it's incredibly accurate and receptive to the changes. I also like to turn it on my desktop when I'm doing something that is going to stress my box (I'm obsessed with keeping my machine cool to the point of not having the heating on in the room my machine is in). Highly recommend. They also have a Windows Phone version which I will try out.
CPU-Z not only gives you info about your processor but also your motherboard, graphics card and RAM amongst other things that would otherwise have been far trickier to ascertain. It supports all major hardware vendors and takes up very little space on your hard drive.
From the bods who bought you CPU-Z, comes PerfMonitor 2. PerfMonitor2 is a processor performance and monitoring tool. It allows to track up to 4 processor-related events chosen in a processor-specific list. It succeeds to PerfMonitor, and some of the new features that were not in the predecessor you see info such as overall CPU temperature, package and core temperatures, package power usage, L2 and L3 cache hit ratios, and more.
It's very straightforward to use: here is a screenshot from my desktop of the temperature when my machine is idle
and this is it when compiling a database solution: