The logic board, dual graphics cards, and I/O port board all connect to this single board.

Wrangling all that data requires a small posse of ICs. We find:

Intel BD82C602J Platform Controller Hub

Renesas R4F2113NLG H8S/2113 16-Bit Microcontroller

ICS 932SQL435AL 3817528F

Texas Instruments LM393 Dual Differential Comparator

MXIC 25L6406E 64M-BIT CMOS Serial Flash

The back of the daughterboard features the same 980 YFC LM4FS1BH System Management Controller found in the Mid 2013 MacBook Air refreshes.