Support for video cards, SLI and CrossFire
Intel's mid range processors have been supporting 16 PCI-Express lanes forever. The high-end Z170-chipset can divide these up, in order to support multiple video cards. However, since the Skylake chipset has much more lanes, it's now possible to provide PCI-Express 16x slots with lanes from the chipset, without sacrificing too much performance.
This is mostly to enable the use of PCI-Express SSDs, because the video cards otherwise will not have access to enough CPU lanes. 3-way CrossFire without sacrificing lanes of the first two video cards also becomes possible with the improvements in the chipset. This whole story doesn't apply to SLI, because Nvidia requires a minimum of eight PCI-Express lanes directly from the CPU to run video cards in SLI.
All motherboards in our test are the same in this area. They all have two PCI-Express 16x slots with lanes from the CPU and a third slot with lanes from the chipset. Therefore they all support 2-way SLI and 3-way CrossFire.
|Motherboard||x16 slots||x16 slots CPU||1 GPU||2 GPUs||3 GPUs||4 GPUs|
|ASRock Z170 Extreme6||3||2||16||8 / 8||8 / 8 / 4||-|
|ASUS Maximus VIII Ranger||3||2||16||8 / 8||8 / 8 / 4||-|
|Gigabyte Z170X-Gaming 5||3||2||16||8 / 8||8 / 8 / 4||-|
|MSI Z170A Gaming M5||3||2||16||8 / 8||8 / 8 / 4||-|
The table down below illustrates which SLI and CrossFire configurations are supported.
|Motherboard||2-way SLI||3-way SLI||4-way SLI||2-way CF||3-way CF||4-way CF|
|ASRock Z170 Extreme6||Yes||-||-||Yes||Yes||-|
|ASUS Maximus VIII Ranger||Yes||-||-||Yes||Yes||-|
|Gigabyte Z170X-Gaming 5||Yes||-||-||Yes||Yes||-|
|MSI Z170A Gaming M5||Yes||-||-||Yes||Yes||-|