Yes, this is possible with the appropriate CPU. 28-lane CPUs can do a maximum of triple SLI. Thus, at least one Intel Core i9-7900X X-Series (LGA 2066, 3.30GHz, Unlocked) would be necessary for 4x SLI.

Manufacturer specifications:
Multi-GPU support
Supports NVIDIA® 4-Way SLI™ Technology *
Supports NVIDIA® 3-Way SLI™ Technology
Supports NVIDIA® 2-Way SLI™ Technology
Supports AMD 4-Way CrossFireX Technology *
Supports AMD 3-Way CrossFireX™ Technology
Supports AMD 2-Way CrossFireX Technology
* 28-LANE CPUs can only support up to 3-Way SLI™/ 3-Way CrossFireX™

Manufacturer's website: https://www.asus.com/de...