50Mhz to 60Mhz

1. if you change the system clock, you should regenerate hardware in sopc builder.

make sure sdram and io timing are met.

2. try to reduce your logic and optimze the timing.

try both S core and F core, use smaller cache size.

try "design space explorer" in quartus.

I have a 2C5-8 with Fmax about 76MHz.