The Series X packs in a board sandwich, but unlike the iPhone X, this isn't to save space, but to make it. The aluminum block in the middle helps direct air between the boards and cool these hot boys. Here's what's on the first board:

Microsoft M1139994-001 T6WD5XBG-0004 Southbridge I/O controller

Texas Instruments LM339A quad differential comparator

Realtek RTL8111HM gigabit ethernet controller

CT08E 2020F1—possibly a Challenge Electronics sound transducer

ON Semiconductor NCP186AMN080TBG 1 A / adj. low dropout linear regulator

Nuvoton ISD8104SYI 2W Class AB audio amplifier

Richtek RT6256BHGQUF and RT6256CHGQUF synchronous step-down converter w/ LDO