Processor and Chipsets on board
The picture below is an Intel Core i7-4770 processor Engineering Sample.
This is the Intel Z87 chispet.
Realtek ALC892 HD audio Codec
Looks like the chipset does not support PCI slots. It uses Asmedia ASM1083 to provide a PCI slot
The ASM1083, x1 PCI Express to 32-bit PCI Bridge, enables users to connect legacy parallel bus devices to the advanced serial PCI Express interface. The ASM1083 is a PCI Express-to-PCI forward bridge, fully compliant with PCI-SIG PCI Express-to-PCI Bridge Specification1.0.
ASM1442 are the high speed TMDS level shift ICs for High Definition Multimedia
Interface (HDMI) and Digital Video Interface (DVI) video application
Realtek Gigabit Ethernet Controller chip
ASUS’s TPU chip