im not sure what you mean by 'flash'. 'Flashing' indicates that you are updating the firmware or somehting.... Maybe your talking about overclocking or soft-modding or something?
Im not sure on the overclockability of the 5200, but you could mess around with some utilities yourself (just make sure you keep on eye on the cooling situation). Im not sure the 5200 can be soft-modded to the ultra but i may be wrong.