I did a whole bucket load of testing for a wiki update. With 3.0-735, the DX11 backend doesn't seem to have the problem with the "blurry top left quadrant" with EFB to Ram. Give it a try, it should help.
Intel Xeon w7-3465X OC | Asus Pro WS W790-E Sage SE | NVIDIA GeForce RTX 4090 FE | 8x16GiB G-Skill Zeta R5 DDR5-6000 | Windows 11 23H2 | (details)
MacBook Pro 14in | M1 Max (32 GPU Cores) | 64GB LPDDR5 6400 | macOS 13