Starfox 1 57 mhz:https://www.youtube.com/watch?v=ZLcw3O7aTgohttps://www.youtube.com/watch?v=qqi1aow6GZI
Starfox 2 running at an insane 53.3 mhz on a standard stunt race fx cart that's wired for eproms and overclocked. To accomplish this I needed to do a little romhacking magic. First I disabled the "double speed" clock mode. Doing this allows me to overclock the framerate 2x what I can do with double speed mode engaged because the overclocking limit is doubled when the internal clock is running at single speed.
I did a bit of research on superfx registers, I came across a register that enables a high speed multiplier mode. After doing a quick search I noticed starfox 2 and starfox are the only roms that don't set high speed multiplier mode. Starfox 1 doesn't enable this mode I'm guessing because the mario chip doesn't have this mode, why starfox 2 doesn't enable the mode is beyond me, maybe because starfox 2 wasn't finished?
For testing purposes I burned a doom rom with high speed multiplier mode disabled and it ran like a complete slug compared to when the mode is enabled. Since my starfox 2 has a disabled "double speed mode" register write I just reprogrammed this to write the register that enables high speed multiplier mode. The results were better than expected. The slowdown is greatly reduced with high speed multiplier mode enabled. There's also an "IRQ Interrupt Mask" function within the same register, I changed this as well (not on purpose). Interestingly changing the irq interrupt mask made starfox 2 stop flickering once overclocked beyond a certain speed, allowing me to overclock the game to the full limit of the superfx chip.
I'm fairly certain that 53 / 54 mhz is the top speed of the superfx chip since both starfox 2 and stunt race fx have the exact same top overclock speed. This romhack was a little bit of skill, a little bit of experimentation, and a little bit of luck. I'm also trying to enable this mode in the starfox 1 rom but for starfox 1 I'll need to find a way to insert the programming since there's no register writes I can hijack. I'm going to need help inserting this little piece of code into the starfox 1 rom.