Oddly configured Dimensity 9300 SoC throttles during stress test losing 46% of its performance

Earlier this year we told you about the unusual configuration of MediaTek's new flagship Dimensity 9300 chipset. The octa-core processor consists of four Cortex-X4 Prime CPU cores and four Cortex-A720 Performance CPU cores. There are no low-power Efficiency CPU cores that other application processors have. While this means that the Dimensity 9300 SoC is powerful, it also means that the chipset is prone to overheating.

In September, we passed along some information about the Dimensity 9300 that came from Hall-of-Fame leaker Evan Blass. A source told Blass that the Dimensity 9300 SoC was experiencing some thermal issues, and while MediaTek denied that the story was true, Blass stuck by his source. Today, "X" subscriber Sahil Karoul revealed (via Wccftech) that a CPU Throttling Test that loaded the 8-core CPU with up to 100 threads resulted in the chip throttling performance down by 46%.

Each thread is a series of instructions given to the CPU by an app or program. Asking the CPU to handle such a workload put stress on the cores causing them to overheat and throttle. While throttling, one of the core's clock speeds dropped to .60GHz with the remaining cores dropping to 1.20GHz and 1.50GHz. The maximum clock speed for the chip is the 3.25GHz that the Cortex-X4 Prime CPU cores were running at by default.

Mediatek Dimensity 9300 #VivoX100Propic.twitter.com/Zi3k4Wmeib

— Sahil Karoul (@KaroulSahil) November 23, 2023

Making this situation worse is that the chip was tested on the Vivo X100 Pro which features a vapor chamber which is a heat pipe used to dissipate heat to the coolest area of the chamber and away from the chipset. Even though the Dimensity 9300 is produced using TSMC's energy-efficient N4P 4nm process node, the throttling of the chip started in just two minutes.

MediaTek probably thought that it could compete with the Snapdragon 8 Gen 3 by leaving out any Efficiency CPU cores like the Cortex-A520. But it will be back to the drawing board next year for the Dimensity 9400. And yes, considering that the CPU Throttling Test is a test that can seriously impact the thermals of even more balanced chipsets, in regular everyday use, phones relying on the Dimensity 9300 AP, like the Vivo X100 Pro, will probably be just fine.