I was having problems getting the cpuspeed daemon running after I switched to the ElRepo mainline kernel on CentOS 6.5. It turns out the newer kernel defaults to using the intel_pstate driver instead of acpi_pstate and this can cause issues with the stock cpuspeed config. If you are using the intel_pstate driver and having issues add this to the kernel boot parameters:
This will force the kernel to use the acpi driver and allow cpuspeed to work properly.
Full credit to Joshua Kramer