Hi Richard,
Would you send us the PCB photo of your MSI RTX 3080Ti Suprim 12Gb(LHR)?
As we know, gaming and suprim have nearly the same PCB,
So our water block BP-VG3090MT-V2 may be compatible.
https://shop.bitspower.com/index.php?route=product/product&product_id=8097&search=3090mt