Mobile PCI Express Module
Mobile PCI Express Module is an interconnect standard for GPUs in laptops using PCI Express created by MXM-SIG. The goal was to create a non-proprietary, industry standard socket, so one could easily upgrade the graphics processor in a laptop, without having to buy a whole new system or relying on proprietary vendor upgrades.
Generations
Smaller graphics modules can be inserted into larger slots, but type I and II heatsinks will not fit type III and above or vice versa.Dell's Alienware m5700 platform uses a heatsink that will fit Type I, II, & III cards without modification.
MXM 3.1 was released in March 2012 and added PCIe 3.0 support.
First generation modules are not compatible with second generation modules and vice versa. First generation modules I to IV are fully backwards compatible.
Some MXM cards have different mounting screw hole configurations, always check the mounting holes of the MXM card and verify that they match those of the card you plan to upgrade to.
| MXM Type | Width | Length | Connector | Module Compatibility | Thermal Compatibility | Max. Power | Max. GPU size |
| MXM-I | 70 mm | 68 mm | Standard 230 | I, II | I | 18 W | 35 × 35 mm |
| MXM-II | 73 mm | 78 mm | Standard 230 | I, II | I, II | 35 W | 35 × 35 mm |
| MXM-III | 82 mm | 100 mm | Standard 230 | I, II, III | III | 45 W | 40 x 40 mm |
| MXM-III | 82 mm | 100 mm | HE 232 | I, II, III, III | III, III | 75 W | 40 x 40 mm |
| MXM-IV* | 82 mm | 117 mm | HE 232 | I, II, III, III, IV | III, III, IV | 75 W | 40 x 40 mm |
| MXM Type | Width | Length | Module Compatibility | Thermal Compatibility | Max. Slot Power | GPU memory bus |
| MXM-A | 82 mm | 70 mm | A | A | 55 W | 64-bit or 128-bit |
| MXM-B | 82 mm | 105 mm | A, B | A, B | 200 W* | 256-bit |
| MXM-B+ | Not Public | Not Public | Not Public | Not Public | Not Public | 256-bit |