6.2. Socket 5
Two upgrade sockets have been defined for the Pentium processor-based systems as part of the processor architecture. Socket 5 has been defined for Pentium processor 75, 90, 100, and 120 MHz-based systems and is defined in the Pentium®Processor Family Developer’s Manual, Volume 1. Socket 5 does not support upgradability for 133 MHz or higher processors.
6.3.Socket 7
Socket 7 has been defined as the upgrade socket for the Pentium processor 133, 150, 166 and 200 MHz in addition to the Pentium processor 75, 90, 100, and120 MHz. The flexibility of the Socket 7 definition makes it backward compatible with Socket 5 and should be used for all new Pentium processor-based system designs. The Socket 7 support requires minor changes from Socket 5 designs – an additional key pin, 3.3V clocks, additional supply current, etc. Contact Intel for further information regarding the Socket 7 specifications.
http://bitsavers.trailing-edge.com/components … ume_1_Jul95.pdf
Socket 7 has been defined as the upgrade socket for the Pentium processor 0110\133) in addition to the Pentium processor (610\75, 735\90,815\100, 1000\120). The flexibility of the Socket 7 definition makes it backward compatible with Socket 5 and should be used for all new Pentium processor-based system designs. The Socket 7 support requires key changes from Socket 5 designs; split voltage planes, voltage regulator module header, 3.3 volt clocks, BIOS updates, additional decoupling, etc. This information is not provided in this databook. Contact Intel for further information regarding the Socket 7 specifications.