Support for graphics cards, SLI and Crossfire
Graphics cards are controlled through the PCI-Express lanes of the processor, which the mainstream Intel processors have sixteen third generation ones of since Ivy Bridge. The Z- and Q-chipsets also allow you to 'split' these lanes, which means you can for example drive two PCI-Express x16 slots with only half the amount of lanes. To use this feature the manufacturer has to implement switches, which only does not happen on the lowest positioned and cheapest motherboards.
Since the number of PCI-Express lanes of the chipset was increased on the 100-series chipset of Skylake, it's also now possible to split these lanes. Most ATX motherboards have a third PCI-Express x16 slot that is connected to four lanes from the chipset. This slot is mainly meant for fast PCI-Express SSDs, but it also allows you to use a third graphics card in CrossFire. There is no space for a third PCI-Express slot on Micro-ATX boards, so we only see a slot connected to the lanes of chipset on the lowest positioned models that do not support SLI.
The ASUS and ASRock boards allow you to split the lanes from the CPU, which means that the two PCI-Express x16 slot can have a lane distribution of x8x8. This also you to run SLI. The Gigabyte and MSI boards lack this feature, but they do offer a second PCI-Express x16 slot with four PCI-Express 3.0 lanes from the chipset, which does allow for SLI, however you can run two AMD graphics cards with a lane distribution of x16x4.
|Motherboard||x16 (CPU)||2 GPUs|
|ASRock Z270M Extreme4||2 (2)||8x8x|
|ASUS Strix Z270G Gaming||2 (2)||8x8x|
|Gigabyte Z270M-D3H||2 (1)||16x4x|
|MSI Z270M Mortar||2 (1)||16x4x|
The table below shows you which SLI and CrossFire configurations are supported.
|Motherboard||2-way SLI||2-way CF|
|ASRock Z270M Extreme4||Yes||Yes|
|ASUS Strix Z270G Gaming||Yes||Yes|
|MSI Z270M Mortar||No||Yes|