MPX — apple

For other uses, see MPX (disambiguation).

Two MPX bays in a , the top is empty and the bottom is occupied. — Two MPX bays in a 3rd-generation Mac Pro, the top is empty and the bottom is occupied.

MPX (Mac Pro eXpansion) is an expansion module configuration and proprietary connector introduced by Apple in December 2019 for their 3rd-generation Mac Pro. The MPX bays provide more power (75 + 475 watts) than is typically available through a standard PCIe slot in combination with a standard additional connector (75 + 300 watts for the latest 12V-2x6).^[1]

Structure

A MPX slot has two parts separated by a short distance: a standard PCIe x16 slot and a proprietary slot specific to the MPX. The proprietary slot is very similar in size to PCIe x16, but the short part (would be power and clock on PCIe) just has two massive contacts running its whole length. The "A" side is for GND and the "B" side is for +12V.^[2] This staggering contact area is what allows MPX to provide so much power.

Not much is known about the role of the long part of the proprietary slot, presumably a data part based on the number of contacts. It is known to be able to at least carry x4 lanes of PCIe and four 4-lane DisplayPort 1.4 connections.^[3]

MPX modules

An MPX module can fit one of two MPX bays in the 3rd-generation Mac Pro. A module can occupy 1 or 2 double-wide slots in each bay. Two matching quad-wide modules can be interconnected through a high-speed Infinity Fabric Link. 3rd-party MPX modules have also been developed for use as high-performance GPUs and internal storage solutions.^[4]