For AMD it is worth having it enabled, instead of the OS loading up one core with tasks, it distributes them across all cores, so system is more responsive. I have it enabled on my Phenom II x4 server and i7 laptop and you can see the difference.
do you mean core park enabled or disabled? because when it was enabled, the workload was spread over just 3 cores, meaning quite high activity but with 3 cores staying idle. surely de-activating core park will create a more even workload across all 6 cores?