Update: Adding a waterblock to an ASUS RTX4090 TUF gpu does NOT void warranty. Asus and BPCTech acknowledge. (Plus Corsair inform they cover and compensate any water damage). Time to watercool :
MSI USA
Retailer reveals most reliable graphics cards and motherboards, warranty process times | TechSpot Forums
Does Water Cooling GPU Void Warranty?
MSI GPU Limited Warranty – LiquidSky.com
Update your warranty with your proof-of-purchase - Microsoft Support