Freesync is compatible with any card that supports displayport and has the necessary architecture, however, NVidia has not included support for it with any of their cards yet. Here is the skinny on what is supported for use with both Freesync and Gsync.
AMD: According to AMD, The following pre-existing GPUs will be able to use FreeSync for dynamic refresh rates in games (after a software update): Radeon R9 295X2, 290X, R9 290, R9 285, R7 260X and R7 260. Other cards/chipsets will support FreeSync, but only for "video playback and power-saving purposes", these include: Radeon HD 7000, HD 8000, R7 and R9 series cards and APUs from the Kaveri, Kabini, Temash, Beema and Mullins lines.
Nvidia: Plenty of older Nvidia cards are compatible with G-sync. The full list of cards is as follows: GeForce GTX 980, 970, TITAN Black, TITAN, 780 Ti, 780, 770, 760, 750 Ti, 750, 745, 650 Ti BOOST, 660, 680, 670, 690, 660 Ti.
As mentioned, the CPU has no bearing on it at all.