I had one of those AMD 5X86 133mhz processors!
At the time, I had it on a board that supported 15/20/25/33/40 and 50mhz bus speeds.
I had started with a 486DX 33, later upgraded to an Intel DX4 100, and then dropped the AMD chip on(someone had given it to me)
It was my first overclock, and quiet by accident. When I booted, for some reason the BIOS set the bus at 40mhz, and the Processor was running at 200mhz!
That was a huge, huge thing! I got online, and did some research to see what was going on, and learned about overclocking. (And Toms about that time as well) So I just left it there, and it ran perfectly fine, and fast.