With PCI Express replacing AGP this year as the graphics card standard, nVidia has today introduced a new interface based on PCI Express for mobile graphics modules. MXM, short for Mobile PCI Express Module is a breakthrough in mobile graphics and possibly one of the most important developments for both laptop manufacturers and end users for a long time.
To date, mobile graphics cards have been proprietary solutions that are custom made to fit each notebook, which is hardly the most efficient way of doing things. In a desktop PC it’s easy to change a graphics card, you just unplug the old one and plug a new one in - and this is exactly what you can do with MXM.
But it goes a little deeper than being just an interface. As both nVidia and ATi have produced pin compatible graphics chips for some time, a notebook manufacturer would only have to swap the chip over for a newer model to make it work. But the problem is that different graphics chips draw different amounts of power and consequently produce different amounts of heat. This means that a simple graphics upgrade is far from simple in a notebook, and can sometimes result in a complete redesign of the chassis.
With MXM on the other hand power draw and heat generation have to be within the specification, which means that as new graphics chipsets are launched, all the laptop manufacturers have to do is swap to a new module. This should result in a shorter time to market, and happier end users.
There will be three different sizes of MXM cards, just to complicate things, but there is a very good reason for this. The smallest type, MXM-I has been designed for thin and light notebooks, whereas MXM-II is for your average notebook and MXM-III is for large desktop replacements. The power and cooling specifications are different for each model to suit the laptop they’re designed for. The idea is that each type of card will offer the best performance, be it for fast 3D graphics or long battery life, all depending on the target user.