The folks at Nvidia have come up with a graphics interface module specification for PCI Express-based notebooks called the Mobile PCI Express Module (MXM).
Unlike desktop PCs, notebooks are subject to restrictive size and thermal constraints. And it’s these constraints that have caused manufacturers to customise their notebook designs to such an extent that adopting a new generation of graphics technology requires an extensive redesign effort.
Now, the folks at Nvidia have come up with a solution that not only benefits the notebook developers but their customers too – a graphics interface module specification for PCI Express-based notebooks called the Mobile PCI Express Module (MXM).
With the MXM system in place, users will be able to simply upgrade the graphics capabilities of their mobile PCs simply by pulling out their old graphics MXM card and plugging in a new one.
The MXM specification itself describes the electromechanical interfaces including feature set, dimensions, connector pinouts and electrical interfaces for each MXM Graphics Module, of which three types have presently been defined in order to achieve varying degrees of performance for different sized systems. MXM-I, for example, is designed for thin and light form factors, MXM-II is designed for mainstream formfactors and MXM-III is designed for the highest performance systems.
The MXM graphics modules have a standard single 230-pin edge connector in which all Input/Outputs are routed through. The MXM specification supports a link of up to sixteen bi-directional PCI Express differential signaling lanes and is compliant with PCI Express Base Specification 1.0a except for power delivery and power management. Notebook power requirements supercede those of the PCI Express power specifications. The MXM does not, however, support Hot-Plug insertion.
The MXM platform has been designed to co-exist with Integrated Graphics Processors (IGP). An IGP notebook designed to support MXM graphics modules can be populated with or without a MXM graphics card. If no MXM graphics module is present, installation of a loop through card is required to complete the internal circuitry.