Quote Originally Posted by Hornet331 View Post
First locked chips where the P2s.
Pentium MMX overdrive
Intel Pentium MMX overdrive 180 - PODPMT60X180

Intel Pentium MMX overdrive 180 - PODPMT60X180
180 MHz
320-pin staggered ceramic PGA

Overdrive MMX processor for Pentium 75, 90, 100 and 150 CPUs

Pentium MMX and non-MMX overdrive processors look somewhat similar to boxed Pentium processors. Like the boxed processors, the overdrives have processor markings on the heatsink. Unlike the boxed processor, the overdrive CPUs have speed marked in the top right corner. The overdrives also include integrated voltage regulator, which allows the microprocessor to work in socket 5 motherboards. And finally, the overdrive processor have their clock multiplier locked. For PODPMT60X180 the clock multiplier is locked at 3x, so depending on bus speed (50 or 60 MHz) the processor will run on 150 or 180 MHz.
Source

And I can say with 100% certainty that the P133 WAS locked (I've overclocked a few dozen Pentiums).