The BIOS Implementation Test Suite is a boot-able pre-OS environment for testing the BIOS's initialization of the Intel CPUs, processors, etc. This test suite focuses upon testing, configuration, and exploration.
Intel's BIOS software is based upon GRUB2 and in designing this pre-OS environment they also added support for initializing all CPUs in multi-CPU/SMP systems, commands for manipulating resources in GRUB (such as MSRs and PCI Express devices), and commands to support hardware configuration and the BIOS test infrastructure.
With this you can easily see if your BIOS is properly configuring processor power management, run Intel's power management reference code, detect the frequency and duration of BIOS system management interrupts, and see the time spent in the different CPU C-states.
Intel's BIOS Implementation Test Suite can be found at BIOSBits.org.