If your workload is latency-insensitive and context-hungry, the M3 Ultra beats a 5090 on total throughput simply because it doesn't page. For agents that chew through large codebases overnight, this is the play.
Status as of 2026-09-24: discontinued. Apple removed the 512 GB memory option around 2026-03-05, cut the M3 Ultra to a single 96 GB configuration around 2026-05-05, and on 2026-08-25 replaced the machine with Mac Studio models built on M5 Max and M5 Ultra (up to 512 GB of unified memory). At its March 2025 launch the M3 Ultra model started at $3,999 with 96 GB; the 512 GB build, which required the 32-core CPU and 80-core GPU chip, listed at $9,499, the figure used as MSRP here. Apple rates M3 Ultra memory bandwidth at 819 GB/s and the machine's maximum power draw at 270 W.