Comment by MrDrMcCoy

The I-prefix stands for Imatrix smoothing in the quantization. It trades a little more accuracy for speed than other quant styles. The _0 and _1 quants are older, simpler quants that are very accurate but kinda slow. The K quants, in my limited understanding, primarily quantize at the specified bit depth, but will bump certain important areas higher, and less used parts lower. It generally performs better while providing similar accuracy to the _1 quants. MXFP4 is specific to Nvidia, so I can't use it on my AMD hardware. It's supposed to be very efficient. The UD part includes more of Unsloth's speed optimizations.

Also, depending on how much regular system RAM you have, you can offload mixture-of-expert models like this, keeping only the most important layers on your GPU. This may let you use larger, more accurate quants. That is functionality that is supported by llama.cpp and other frameworks and is worth looking into how to do.