- CPU Upgrade: Give your 486 PC a kick with the AMD 5x86 - 133! The whole story. by Jan Steunebrink Version 4, July 1999 Contents Introduction Which Am5x86 do you like The CPU Socket The motherboard jumpers BIOS Compatibility Introduction With this story, I like to tell what I have learned by upgrading my 486 PC with the Am5x86 CPU. I will try to provide as much practical detail as possible. The ...web.inter.nl.net/hcc/J.Steunebrink/amd5x86.htm