AMD has announced that its upcoming RX 9070 series (RDNA 4) GPUs will require a UEFI system for optimal compatibility. Put simply, it has dropped support for the older BIOS and CSM standards, requiring users to make the necessary shift to UEFI. While this doesn’t mean RDNA 4 GPUs will cease to function with legacy firmware, AMD offers no assurance.
Would you notice that big of a performance difference from PCIE3? Usually for gaming the bandwidth is nowhere near close enough to being saturated and sure, PCIE5 will have 4x the throughput of PCIE3, but I imagine the performance loss would be more due to the CPU than the PCIE bandwidth.