Name: 6 Series/C200 Series Chipset Family Desktop SATA Controller (IDE mode, ports 4-5)
DID 1c08 presents ports 4-5 in IDE mode. The controller itself offers 6 SATA ports but the IDE emulation cannot handle them. Hence the split between DID 0x1c00 and 0x1c08.
See the Intel 6 Series Chipset and Intel C200 Series Chipset Specification Update for details