We have previously reported about Apple testing multiple Macs using its upcoming M3 processor line. Most recently it was revealed that the Mac mini with a base-level M3 is on Apple’s test benches, but that’s just the latest in a string of future Macs in testing.

The latest is the most powerful yet: A MacBook Pro with an M3 Max. That’s the largest single-die configuration of the upcoming chip, and the most powerful to appear in a MacBook Pro—the M3 Ultra would be two M3 Max chips connected together and reserved for the Mac Studio and Mac Pro.

A new report from Mark Gurman at Bloomberg, who has about the best record of Apple’s secret activities of anyone, details the specs of the new chip in testing according to test logs from a third-party Mac app developer he has seen: The M3 Max in question has 16 CPU cores, divided into 12 high-performance cores and 4 high-efficiency cores. That’s 4 more high-performance cores than M2 Max.

The chip has 40 GPU cores, while the M2 Max is available with either 30 or 38 cores. It’s not known whether the 40-core version in testing is the top-end model.

Apple’s test chip has 48GB of RAM, which is an interesting number. The M2 Max is available with 32, 64, or 96GB of RAM. A 48GB figure suggests that the M3 Max will be available with 48, 96, or 144GB of RAM. Apple may be widening the memory bus by 50 percent, which means much higher memory bandwidth, or it could be employing denser RAM.

Bloomberg’s report reminds us that Apple is almost certainly testing multiple different variants with different core counts and RAM, of which this is only one of them. It is certainly possible that this exact configuration of cores and RAM never comes to market.

Apple is testing multiple different Macs with M3 chips in them, from the base M3 in a MacBook Air up to this M3 Max in a MacBook Pro. It is expected that the company will release some of these products in October, though we don’t yet know exactly which ones. If historical trends are followed, we’ll get base M3 models first (and maybe not all of them), with M3 Pro and M3 Max-based products in the spring, and M3 Max/Ultra-based desktops like the Mac Studio and Mac Pro in the summer of 2024.