Go to:
Guru3d and look for a file called: NVHardPage.
It's an NVidia tweaker, that integrates with your driver display control panel, it will autosense what the max overclocking your 5600FX can take.
I use it presently for my 5600FX.
But be aware that this IS overclocking, so there still a possibility you can fry your card. You may just want to take your card manually up to that OC point step by step-by-step just to be safe.