So I was bored and tried 44x as the cache multiplier. 4.4GHz cache crashes instantly when a heavy load is applied with stock voltage (Prime95 in this case).
Therefore I'm going to assume 40x is the correct Cache Ratio, at least for my CPU. -- Intel may set the cache ratio to follow Turbo (if stable) during binning, which is why my 4770K's cache multiplier followed Turbo boost.