I don't know what motherboard you have, but timings and voltages are usually set in the BIOS. So you'd have to boot into the BIOS and look for the options to change it there.
You can use this tool CPU-Tweaker 1.1 to help you along with CPUz 1.51. CPU Tweaker 1.1 download CPUz 1.51 download
CPU tweaker allows you to make on the fly timing adjustment for various motherboards. The only thing you cannot change on the fly is the CAS latency. That has to be done in the BIOS.
Just want to add CPU Tweaker on the fly adjustments work with these boards only: From XS site.
INTEL Core i7 DDR3. Change timings on Core i7 CPU is possible with GygaByte, eVGA ,DFI and Biostar motherboards.
(Memory Configuration space are locked in the bios on others motherboards).