A friend just got an M3 Max with 128GB (V)RAM and he's extremely happy with it (AI workloads wise). That could be an option if you can run your simulations on macOS.
That machine with 128GB is $5000, with 48GB is still well over $3000, and has as much memory bandwidth as a $400 GPU. At the current spot price, 128GB of GDDR6 is <$400 and 48GB is <$150, implying that they could be paired with any existing <$1000 GPU to produce something significantly faster for dramatically less money. If anyone could be bothered to make one.
If all you want is VRAM you can get old P40s with 24GB for $175 and it's 144GB for $1050. Then you need a big machine to put six of them in but that doesn't cost $4000.
But all of this is kludges. The Radeon RX 7900 XTX has more than twice the memory bandwidth of the M3 Max with much better performance per watt than an array of P40s. What you want is that with more VRAM, not any of this misery.
That checks out in principle, but given that P40 doesn't support NVLink, I wouldn't count too much on using six of them together in a performant manner.
But yeah the best option remains an MI300 if you can afford that.
Yeah, my M2 MacBook has 96GB @400GB/s. For $4k or so, it feels like cheating. Does it beat 4x24GB NVIDIA cards? Absolutely not! It's slower and occasionally runs into CUDA-moat software issues. But the capability to daily drive Mixtral 8x7 locally, with great token speeds, is phenomenal.
