Don’t trust those early Geekbench M3 Ultra benchmarks just yet

Macworld

As is customary with all new Apple chips, the first leaked Geekbench benchmarking numbers for the M3 Ultra in the new Mac Studio have arrived. But before you think the numbers are disappointing or proof that Apple is fudging the numbers, let’s put them in context.

As reported, the benchmarks for a Mac 15,14 running an M3 Ultra with a 32-core CPU and 256GB of RAM are 3221 (single-core) and 27749 (multi-core). Those are impressive numbers, of course, but comparable to our own numbers for the M4 Max in MacBook Pro, which measured 3804 (single-core) and 25343 (multi-core).

We expect the single-core score to be lower since it’s an M3 vs an M4, but the multi-core score should theoretically be a lot higher than an 8 percent gain. The M3 Ultra has 24 performance cores versus just 12 on the M4 Max. While it’s not an apples-to-apples comparison—the M3 and M4 chips are built on different 3nm architecture generations—it’s still surprising to see such low scores. So what’s going on?

The simple explanation is that Geekbench 6, which was used to test the Mac here, is not built to handle large CPUs. As explained in a post by ServeTheHome, which tests top-of-the-line PC hardware, “higher-end workstations and even higher-end desktop CPUs run into scaling issues with Geekbench 6.” In particular, Geekbench appears to have issues when there are more than 16 performance cores, which is the case with the M3 Ultra. (Of note, the M2 Ultra had exactly 16 performance cores so didn’t run into the same issue.)

In ServeTheHome’s testing of the 64-core AMD Ryzen Threadripper 3995WX, they also got numbers that weren’t indicative of the chip’s actual performance. This wasn’t the case with Geekbench 5, but developer Primate Labs has “shifted to smaller CPUs” with the Geekbench 6 update. It makes sense to focus on phones and mid-range PCs since Geekbench is such a popular tool with consumers. It’s great for iPhones and MacBook Airs, but not so much for $7,000 supercomputers.

It’s also worth noting that the M3 Ultra is likely to post its biggest gains on the graphics side. With a 60- or 80-core GPU, the M3 Ultra is likely to blow away the M4 Max in real-world performance tests. We’ll just need to wait a little longer to see those numbers.