I have a Q9400 on a Gigabyte motherboard. The Q9400 has a relatively low multiplier so you have to run the motherboard at a pretty high frequency to get the CPU up to a good speed. The motherboard has to be up to it and also the ram has to be up to it. The first thin is to make sure your ram is running at 1:1.
You didn't say what speed you are aiming for. I did short tests of my machine at 3.8GHz but I normally run it at 3.4GHz.