What’s the Oldest Kernel Version That Supports the Sapphire RX 7800 XT Nitro+ GPU?

Just a heads-up, kernel 6.3 is considered end-of-life (EOL), so you might want to stick with something newer for better support and stability.

Yes, you’re right! The oldest kernel version that will work with the Sapphire RX 7800 XT Nitro+ is indeed 6.3. However, you'll also need to have Mesa 23.1 or later installed because Mesa plays a crucial role in making AMD GPUs perform well. But honestly, using such an old kernel isn’t ideal; newer versions have better optimizations for RDNA 3 series GPUs.

By the way, there's a resources page that can help you out. Remember to back up your files regularly and try anything new in a virtual machine first to avoid issues!