ASUS ROG Maximus XI Apex Motherboard Review

The Hardware Asylum Multi-GPU index is a portable set of data we can use to determine the multi-GPU potential of any motherboard.  A higher index number indicates a favorable condition for multiple graphics cards while a lower number indicates a hindrance in one of our leading indicators.  Since the Index is not dependent on system architecture it can be applied to any motherboard regardless of processor or chipset generations.

Index: 3.5
Optimized: 2x
Max Support: 3x

NVidia SLI
AMD Crossfire

As indicated by the PCI Express layout chart there are a total of three 16x PCI Express slots on this motherboard with two of them using bandwidth earmarked for video cards.  Slot two will be the primary video card slot and will run at a full 16x when only a single card is installed. 

For best video performance you will want to populate slots two and five with video cards.  The final slot is using bandwidth from the Z390 chipset and is not ideal for video card usage but can be done.  For instance 3-Way Crossfire is possible along with a dedicated PhysX processor or any external storage controller provided that it can operate with 4x or less lanes of PCI Express bandwidth.