9. Microsoft Mach 10 (1986)

Microsoft created Mach 10 accelerator board, which nearly doubled the speed of IBM PC and PC XT computers with 4.77-MHz 8088 CPUs and were running Windows 1.0 which came in 1985. The Mach 10 included a 9.54-MHz 8086 CPU and a Microsoft InPort mouse interface on one plug-in card. It provided an impressive increase in speed for original PC owners at a time when the next step up, an IBM PC AT, cost quite a bit of money. 

10. Microsoft Mach 20 Performance Enhancement System (1988)

Mach 20 was created as a gateway to allow 8088-based PCs to run the latest versions of Microsoft programs. The Mach 20 plugged into a standard IBM PC ISA slot and provided the host system with an 8-MHz 80286 CPU, a slot for an 80287 math co-processor, and an InPort mouse interface. It also offered a Disk Plus option that allowed older IBM PCs to utilize high density floppy drives.