The Complete Video Library of Extreme i486, i586, k6III, pIII Overclocking
Here is the list of the most interesting YT videos related to overclocking of classic computer architectures.
DX5-133Mhz »» DX5-200Mhz
PentiumMMX-300Mhz »» PentiumMMX-420Mhz
K6III-450Mhz »» K6III-600Mhz
PIII-1200Mhz »» PIII-1900Mhz
However, this is more substantial overclock [right up to ~2500Mhz] , of course it is LN2 based cooling solution.