Single-fan vs dual-fan iMac 24: M1 Apple Silicon's performance potential in 7-core base model spoiled by thermal throttling in benchmark battery

We recently reported on a “hidden” difference between the new Apple iMac 24 with 7-core GPU and the model with an 8-core GPU. The base model of the M1 iMac is fitted with a single fan, while the next model up in the range has two fans inside it. Vigorous benchmark testing by popular YouTube outfit Max Tech has shown how the single-fan iMac 24 loses ground in CPU and GPU performance because of the effects of thermal throttling.

While Geekbench 5 results were pretty much as expected, and the dual-fan iMac 24 was able to take an appropriate lead in the Metal compute benchmark because of having an M1 chip with an additional GPU core, testing with 3D Mark Wild Fire started showing some disconcerting differences. In a stress test, the single-fan iMac 24 started throttling as the cooling system maxed out its fan's RPMs and still couldn’t keep the SoC’s temperature down. The 8-core (GPU) iMac 24 performed around 10% better here, with its two fans often sitting idle.

A Cinebench 23 run was even more damning for the 7-core iMac 24 with one cooling fan. The M1 Apple Silicon chip was measured running at around 2.5 GHz @10.3 W whereas the 8-core iMac 24 with two fans was able to reach its full potential performance rate of 3.2 GHz @15 W and still record a lower processor temperature (88 °C vs. 94 °C). The final scores in this telling benchmark run were 7,002 points for the single-fan iMac 24 compared to 7,722 points for the dual-fan model, or +10.28% advantage for the device with the superior cooling system.

The tech channel utilized a thermal imaging camera to show how the single fan in the base model of the iMac 24 couldn’t properly cool the M1 chip, while the dual-fan variant was obviously more successful at keeping temperatures down. Although the 8-core model had more RAM, at 16 GB to 8 GB, the tests chosen mostly stressed out the CPU and/or GPU. So once again, potential buyers should really consider paying out the extra US$200 for the 8-core dual-fan model if they plan to use their 2021 Apple iMac 24 for more than basic tasks.

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