Why MXM, why not PCIe?

[Matteo De Vellis]

Why do laptop GPUs use MXM over a standard PCIe 16x slot?, I know it's a bit of a thicker connector, but the heatsink on the GPU will still be taller than the slot, so I don't see why PCIe 16x isn't used instead and isn't PCIe faster anyways?

 

[jimmysmitty]

MXM is PCI Express, it is just a slot variant designed for mobile applications of PCIe.

The reason they don't use the slot from the desktop is because it is too long for use in mobile devices.