Technically the Phenom II's max RAM speed is 1333MHz, but it is possible to overclock the RAM. I was able to get my Phenom II up to 1600MHz, beyond that is hit or miss.
Personally I would leave it at 1600MHz as you will not notice any performance difference by going past that.
Oh, i supposed that, in fact that´s the maximum speed i can get with them, also i´ve noticed that the G.Skill Memory Modules i bought are mentioned to be compatible with IntelZ68 & P67 &p55 platforms, does that mean this memory modules are not fully compatible with Amd Motherboards?
By the Way will be the Ram be damage if i use under voltage? or either the system? Thanks