This page concentrates all "must-know" facts about MXM, specification version 1.3, 2.0 and 2.1. While the advent of specification version 3.0 has now made the previous versions obsolete we still carry these parts as upgrades and replacement. With many manufacturers still on the 'legacy' platform with little incentive to switch to 3.0, we expect 1.3-2.1 to remain around for some time.


  Width Height Mounting holes Notes
Type I 70mm 68mm 41mm  
Type II 73mm 78mm 41mm  
Type III 82mm 100mm 46mm  
Type HE 82mm 100mm 46mm  
Type IV 82mm 117mm 46mm Introduced in v2.1


From left to right: Type I, II, III, HE, IV. Please note the IV card has had it's power tab removed.

The second part of the story is the connector:

Type I Regular
Type II Regular
Type III Regular
Type HE HE
Type IV HE


Left: Regular. Right: HE connector

The differences are minimal: the HE connector has additional pins with the only purpose to carry more power. There are no functional differences besides the power capacity.

HE versus regular card edge

Mechanical compatibility question #1

Is there enough room inside the chasis? If your original card is of a smaller size you should check how much space there is to expand on both height and width.

Mechanical compatibility question #2

A HE connector will accept a regular card without any problems. A regular connector will actually also accept a HE card BUT this should only be used for quick verifications where the card is never stressed. A HE or IV card requires per definition more power than the regular connector can deliver. Trying to draw that power through the regular one may cause premature aging, malfunctioning due to excessive voltage losses over the connector or severe overheating with the associated fire hazard. If you insist on doing this (at your own risk, obviously) it should be considered marginally less risky if you do this with your outlet power plugged in. Higher voltage, lower current. Ohm rocks!

Mechanical compatibility question #3

A MXM card has a grand total of 6 (or 7 in the case of IV cards) holes. Two (or three for IV) are identical over all cards and are used to bolt the card to the motherboard. The remaining 4 holes are used most of the time to secure the heatsink to the card. Here, there are two potential dimensions. The holes are either 41 or 46mm apart. Larger cards have larger spacing to accomodate larger GPU dies. When going from Type II to Type III cards, this parameter is changed. On some notebooks (like most Uniwill based notebooks) this causes little concern as their heatsinks are equiped with mounting holes for both 41 and 46mm cards. Other manufacturers, however, use different heatsink strategies and problems can be expected.

Mechanical compatibility question #4

Heatsinks are often made to accomodate a certain MXM card, with the surface of the heatsink being modelled after the surface of it. This means that the heatsink might be very close to the memory chips so they can be cooled easily and has a cutout to accomodate for large components on the MXM card. Unfortunately, when swapping cards the high components on the replacement or upgrade card may be in a different position where no cutout is foreseen. This causes interference and may require some modifications on the heatsink.



Please note that the second/dual DVI feature is optional and may or not be present on any given module. We also believe that having two external displays is the maximum for any given module. So, 2 DVI panels or a DVI panel plus VGA but never 2 DVI panels plus a VGA output.


Please note that single DVI support is mandatory and anything above optional and often exclusive with the LVDS panel. HDMI support is expected to be exclusive with one of the DVI ports. The MXM Upgrade team assumes that a maximum of 3 displays is supported.


Saving the best for last, the general 'compatibility' placeholder is where most upgrades or replacements fail.

In theory, all MXM platforms are required to support either of two information exchange methods:

  • A EEPROM on the motherboard
  • A part of the system bios for MXM information, accesible through a 15H bios callback

The MXM structure contains information about the mothersystem like thermal and power capabilities, display formatting, backlight control etc.

In practice, we assume that especially 'early' MXM platforms did not care too much, either fixing certain parameters to a known right configuration (what's the point of having a structure that tells the MXM card what LVDS configuration you need if you are designing both MXM card and system and know in advance what LVDS panel will be connected...) or relying on auto-configuration based on DDC. Same idea regarding the thermal information: not much point in information stored on the mothersystem ("Hey, I can handle 20W!) if you know in advance you will only insert a MXM card that stays within the system's limits.

Unfortunately, we assume that this lackluster approach causes some off the incompatibility issues reported. If, per example, a vBios is fixed to a single link LVDS panel and you insert the card in a dual link system you will not have any image on your LCD panel.

At least as unfortunate, we believe that some manufucturers make sure that their systems will only work with their cards and vica versa. There is a decent chance they have a noble reason for this, to shield their system from lackluster MXM implementations or from MXM cards that have interpreted the specification a bit too loose, but the odds are at least as high for simple commercial reasoning behind this. Let's list some reasons why some system/card combinations do not work...

All this eventually leads to a probability for succesful upgrades that is close to about 25% if you implement any given card in any given system. By screening and tweaking the cards we offer, our cards in any given system are closer to 50%. For our cards in systems we have validated this rate is obviously 100%.

To get to a validated card/system combination we do a lot of testing. We have boxes full of cards that we had to discard for one reason or another and try to get our hands on as many platforms as possible. But ultimately, we rely on people like you to check the options. If you are interested in helping us out, head over to this page...