Thank you G.S!
Can you tell me what is the difference between
F2-6400CL4D-2GBPK ---DDR2 800 4-4-4-12 1.9V
F2-6400PHU2-2GBHZ ---DDR2 800 4-4-4-12 2V

Aside from the voltage, both of the above timings are the same. Is there an advantage to spending more for the PHU2 kit?