An M1 Ultra has 800gbps unified memory. It’s nothing to do with Apple, it’s their microarchitecture. They’re just about the only game in town with high-bandwidth memory if you want >24GB (for less than $10k, anyway).
A 5090 gets you 32GB with 1.8 TB/s of memory bandwidth for ~$4k, RTX A6000 gets you 48GB at 768 GB/s for ~$3.5k, 2x 3090 gets you 48GB for $2000 or so, and if you're willing to go into the wilderness, there are much cheaper options like the AMD MI50.
The RTX 5000 Pro 72GB seems like kind of a sleeper to me, and sips < 300W of power, approx 1/2 that of its big bro the RTX 6000. Kind of dream about installing it in a 10" rack, it seems like it might be able to work? @jeffgeerling you out there?
Yeah this is just not the case at all; a 5090 or any of the recent nvidia workstation cards all fit this criteria.
Also, while memory bandwidth is important, it isn’t the only consideration. Apple’s architecture has memory bandwidth equal to a mid-range consumer GPU, but its GPU speed is much, much worse than, say, a 5080 or 5090. This translates into e.g. much slower time to first token on Mac systems compared to dedicated GPUs.
$3k for a 5090 fits your criteria and is in the same category of "you can use it for other stuff" (gaming), and is going to run circles around the M1 Ultra Mac Studio.
Or you can spend ~$2k on a pair of 3090s, which gives you 48GB of memory and will also be significantly faster than the M1 Ultra.
IMO there is no situation in 2026 where buying a 32GB M1 Ultra is the right move.
edit: for the folks brave enough to try them there are also additional aftermarket/modded options; I've seen both 4080 Super cards upgraded to 32GB of memory, and 4090 cards upgraded to 48GB. The former comes in at $2k-2.5k and would still be faster than the M1 Ultra.
I'd also like to call out that "high bandwidth memory" (HBM) is a specifically defined thing[0], and is used in high end GPUs, and notably not used in Apple's machines.
I know you probably weren't referring to this type of memory in your post, but IMO it might be worth avoiding this term in the future unless you're referring to HBM, the standard.