doesn't really depend on the chip....i haven't seen too many e6300's that won't do 3ghz.
for 3ghz, you have to run at 429fsb. pretty much any 965 board out there will allow this and a lot more. even 975 can do this with some effort.
your ram also has to be able to do 429mhz, or ddr2-858. again, pretty much any ddr2-800 will do these speeds, and a lot of ddr2-667 will as well.
what is the rest of your setup?