This is where socketed CPUs started. CPGA168 chips ushered in the 486 era and were sometimes informally known as Socket 0 or Socket 486. Featuring a nice purple ceramic body and golden pins/caps, these chips were among the last not to require a heatsink. As it turns out, 486 CPUs existed for Socket 1, 2 or 3.
Intel i486 SX 25MHz SX411
Intel i486 SX 25MHz SX679
Intel i486 DX 33MHz SX419
Intel i486 SX2 50MHz SX845
Intel i486 DX2 66Mhz SX762
Late 486 CPU with FPU, internal clock running at a multiplier of 2 for a clock rate of 66Mhz with outside bus running at 33Mhz.
Intel OverDrive DX 33Mhz SZ698
Intel OverDrive DX2 50Mhz SZ934
Intel Overdrive CPUs were often sold as “plug in” upgrades for older systems, and were very similar in terms of performance. They were sold with permanently attached heatsink. This one appears to be a clock doubled version, running at 50Mhz, so ideal for upgrading boards running the original 486SX-25.
Intel OverDrive DX2 66Mhz SZ904
Another upgrade CPU, this one probably better suited to upgrading boards originally running with 486DX-33s.