File size ≠ RAM/VRAM usage. KV cache, compute buffers and runtime overhead are separate — at the full 128K context a 2.5B model still needs several GiB of KV. Pick a sane -c. Naming: minicpm5-2b-abliterated-FIT-<tier>-<size>GiB-<type>.gguf, where <type> is always a nameable GGUF preset — the native preset when the recipe overrides no tensor, the element-weighted dominant type when that is itself a preset name, and the recipe's base preset otherwise. The three bare tensor types (Q4_K, Q3_K, Q5_K) are deliberately never used as suffixes: llama.cpp only ships the _S/_M/_L variants, and a filename with no recognisable quantisation token is dropped from Hugging Face's own variant panel.
The four tiers are all KL-bound — KL, not the Same-top floor, is what separates PASS from FAIL on this model, so the recorded margins are the KL ones above.
Read the curve, not just the tiers. On a 2.5B model the fidelity tiers are deliberately capped at KL 0.05–0.20, so the two big native presets are cleaner than every tier — Q6_K at 1.93 GiB is 6× cleaner than QUALITY at 1.46 GiB. If you want maximum fidelity rather than minimum size, take Q8_0 or Q6_K.