AMD K6-2 450mhz @ 550mhz, uhh, about 6 years old and still runnning today (at my friends house, he bought it for his younger bro) on stock cooling. This was the first cpu i ever overclocked and it wouldn't go higher because the mobo used dip switches and i had it set to it's max settings. Needless to say it gave a me a huge boost in performance! I was surprised, i used to game a lot on it and play nintendo 64 emulators... i used to get like ~35fps which was just playable, but after overclocking i was always hitting 60fps, of course there were times it would dip down a bit if it had a lot to render.. i had a voodoo 4 4500 in it too, 3dfx... <3