Mac Studio M5 Max, 128GB vs DGX Spark GB10 Grace Blackwell, 128GB for local AI
Both hold 39 of the 48 current models here. The DGX Spark, 128GB costs $400 less. On Qwen3.8 27B, the strongest model both hold, the Mac Studio M5 Max, 128GB is about 2.3× faster: 25 tok/s against 11, both estimated from memory bandwidth. The Mac Studio M5 Max, 128GB pays for itself sooner, in 287 years against 346 years at 500k tokens a day.
| Mac Studio M5 Max, 128GB | DGX Spark GB10 Grace Blackwell, 128GB | |
|---|---|---|
| Price | $5,099 | $4,699 |
| Memory | 128 GB | 128 GB |
| Usable by the GPU | 96 GB | 119.5 GB |
| Memory bandwidth | 614 GB/s | 273 GB/s |
| Power under load | 145 Wstand-in | 150 W |
| Models that fit | 39 | 39 |
| Best model it runs | Qwen3.8 27B | Qwen3.8 27B |
| Speed on that model | 25 tok/s estimated | 11 tok/s estimated |
| Pay-back on that model | Pays back in 287 years | Pays back in 346 years |
The 145 W beside the Mac Studio M5 Max, 128GB is a stand-in, not a figure for that machine: the data borrows it from the nearest hardware it does have, and the machine's own page names which and why. So the two figures above are not like for like, and the electricity in its pay-back here is priced from a borrowed number.
Run the numbers on the Mac Studio M5 Max, 128GB · or the DGX Spark GB10 Grace Blackwell, 128GB
How much use it takes to pay back
Everything above is at 500k tokens a day. Pay-back moves with how much you actually run, so here are both machines on Qwen3.8 27B, the strongest model both hold, at the five levels of use the calculator names. The Mac Studio M5 Max, 128GB pays back sooner at every level of use, so this is not a choice that turns on how hard you work it.
| A day's use | Mac Studio M5 Max, 128GB | DGX Spark GB10 Grace Blackwell, 128GB |
|---|---|---|
| 50ka few chats a day | 2,867 years | 3,456 years |
| 200klight assistant use | 717 years | 864 years |
| 1Ma moderate coding-assistant day | 143 years | 173 years |
| 4Mheavy coding with an agent | 36 years | 43 years |
| 20Magents running most of the day | 7.2 years | 11 yearsits ceiling |
On Qwen3.8 27B the DGX Spark GB10 Grace Blackwell, 128GB generates at most 15.2M tokens a day, so its figure at 20M tokens a day is for the most it can do, not for the whole of what was asked.
Run the Mac Studio M5 Max, 128GB at 20M tokens a day · or the DGX Spark GB10 Grace Blackwell, 128GB
The same models, not to the same length
Every model on this list that fits one machine fits the other at 32k of context, so memory does not change what they run. What it changes is how far you can take the context on one of them. The DGX Spark GB10 Grace Blackwell, 128GB has 119.5 GB usable against 96 GB, and spare memory is what the KV cache grows into as you keep more tokens.
| Model | Mac Studio M5 Max, 128GB | DGX Spark GB10 Grace Blackwell, 128GB |
|---|---|---|
| Devstral 2 123B75 GB of weights | 32k | 64k |
Each figure is the longest context the calculator offers that the machine still holds that model at, and no model is taken past its own context limit. The other 47 models the calculator counts reach the same length on both machines, at every setting from 4k to 256k.
Run Devstral 2 123B on the Mac Studio M5 Max, 128GB at 32k · or on the DGX Spark GB10 Grace Blackwell, 128GB at 64k
The Mac Studio M5 Max, 128GB is also head to head with another computer: Mac mini M5 Pro, 24GB · GMKtec EVO-X2, 128GB · MacBook Air M5 (15-inch), 16GB · MacBook Pro M5 Pro (16-inch), 64GB · MacBook Pro M5 Max (16-inch), 48GB. With a graphics card: RTX PRO 6000 Blackwell, 96GB · Radeon AI PRO R9700, 32GB. With the same machine at another memory size: 48GB · 64GB. With the machine it replaced: Mac Studio M4 Max, 128GB.
The DGX Spark, 128GB is also head to head with another computer: Mac mini M5 Pro, 24GB · GMKtec EVO-X2, 128GB · MacBook Air M5 (15-inch), 16GB · MacBook Pro M5 Pro (16-inch), 64GB · Corsair AI Workstation 300, 128GB. With a graphics card: RTX PRO 6000 Blackwell, 96GB · Radeon AI PRO R9700, 32GB.
The assumptions behind both columns
Both columns use the same usage: 500k tokens a day at 15:1 input to output, 32k of context, $0.17 per kWh, and today's API prices held flat. Speeds marked estimated are worked out from memory bandwidth rather than measured, and pay-back scales with them. Change any of it in the calculator.
More head to head: everything the Mac Studio M5 Max, 128GB runs · everything the DGX Spark GB10 Grace Blackwell, 128GB runs · every other match-up · the quickest pay-back at each level of use · every model against the frontier