I mean, the ECS chipset in the A600 is basically the same as the one in the A500+, and only slightly modified from the OCS one in the original A1000, but with newer manufacturing processes.
Overclocking chipset is not that easy. Certain chips just arent reliable at higher clock rates. Cooling is only minor problem here. And if you were able to overclock chipset how would chip ram work?
Double data transfer rate from chip ram? No way.
On Amiga everything was carefully designed to work in good order. If you clock 68000 to 14MHz you have small chip ram bottleneck.
