With a 128Gb Mac, you can even run 405b at 1-bit quantization - it's large enough that even with the considerable quality drop that entails, it still appears to be smarter than 70b.
You need to quantize 70b to run it on that kind of hardware as well, since even float16 wouldn't fit. But 405b:IQ1_M seems to be smarter than 70b:Q4_K_M in my experiments (admittedly very limited because it's so slow).
Note that IQ1_M quants are not really "1-bit" despite the name. It's somewhere around 1.8bpw, which just happens to be enough to fit the model into 128Gb with some room for inference.
