In order to allow the easy processor upgrades of earlier motherboards, Intel has made available Pentium-class OverDrive chips. These are internally Pentium chips, but have subtle changes made to them to accommodate the unusual sockets and motherboards they are designed to work in. Your motherboard manual will tell you what your system's limitations are.
OverDrive processors have several changes made so that they can be used in older machines.
Second, they of course have the right pin configuration for the socket. This saves the user from worrying about what jumpers to change when replacing the processor. This Pentium OverDrive is specially modified to fit the 32-bit data bus of a 486 system. As you know a Pentium normally uses a 64-bit data bus, but this is not consistent with a 486 motherboard's design. Therefore, this OverDrive is modified to use an external 32 bit bus.