Ram PC8500 and Ram PC6400 question

[Earth]

a simple question, I have 2 sticks of RAM g-skill ddr2 PC8500 and I just added a 3rd stick, but not the same, it was PC6400. What is the practical difference between 8500 and 6400, and it poses a problem to have them together?
I have vista, no overclocking on motherboard asus P5E done, an Intel Core 2 Duo E8400 3ghz and a Radeon HD4850.
Thank you

[Techguru01]

None, except if you overclock.
PC 8500 PC = 6400 certified turn to 1066MHz

[ApPy10]

of 8500, there is a frequency of 1066MHz, while PC6400 is 800mhz and the 1066, will save the frequency of others

[T.J.]

It makes no difference because you not overclocked it yet.

Even the PC6400 is faster than the FSB of your CPU (333Mhz to 400Mhz against the latter for the PC6400) and since it is likely that you are synchronized in frequency (often the default setting) even when your PC8500 running at 333Mhz at the moment.

Use RAM faster than the PC6400 is only of interest for overclocking.

[Earth]

nice, thank you for your reply