Lumex instead of Cortex: ARM's new cores for smartphones and tablets

ARM is renewing its range of standard CPU cores for smartphones, tablets and notebooks. While ARM previously provided three different CPU cores in its mobile processors, there are now four with Lumex. They are called C1-Ultra, C1-Premium, C1-Pro and C1-Nano. The names provide information about the performance: The Ultra is at the top of the list and is slightly more powerful than the previous Cortex-X class cores. The new C1-Premium sits between the previous Cortex-X and the Cortex-A700 series. C1-Pro corresponds to the A700 series, while C1-Nano is the counterpart to the previous Cortex-A500 cores. The Lumex clusters support the ARMv9.3-A architecture.

Chip designers should be able to fine-tune their processors to their own requirements with the now four standard cores. Buyers of the standard cores so far include Mediatek, Nvidia, Google and Samsung.

In order to achieve higher performance, ARM is increasing the maximum clock frequencies, relying on larger caches, larger instruction windows and a revised jump prediction, among other things. The C1-Ultra is designed with a modern 3-nanometer manufacturing process for permanent clock frequencies of up to 4.1 GHz – Short-term boost modes go a little further. With the C1-Premium, 3.5 GHz is possible, Pro (2.5 GHz) and Nano (2 GHz) run correspondingly slower. Alternatively, ARM offers design libraries that are trimmed to minimize space requirements at the expense of performance. These variants are ideal for low-cost devices, for example.

The octa-core reference design from ARM consists of two C1-Ultra and six C1-Pro. For mid-range devices, ARM suggests the C1-Premium instead of the Ultra. The C1-Pro can either be the weaker, power-saving part of a fast processor or, in combination with the small C1-Nano, work as the stronger part in an entry-level processor. Like its predecessor, Lumex supports designs with up to 14 CPU cores. Companies such as Mediatek and Nvidia are increasingly moving away from ARM's reference design and combining only the two fastest core classes in their high-end CPUs.

For the Lumex reference design, ARM calculates performance gains of 25 percent for single-threaded tasks and 45 percent for multithreading, in each case compared to last year's generation, consisting of Cortex-X925, -A725 and -A520. ARM claims to have increased gaming performance by 16 percent. With the same performance, the electrical power consumption is to be reduced by 28 percent.

Still no NPU from ARM

ARM's design still does not include an independent AI unit (Neural Processing Unit, NPU) for AI calculations. All AI tasks first arrive on the CPU cores and are then passed on to the GPU if necessary. However, chip designers can still attach their own NPU to the ARM cluster. With the new architecture extension SME2 (Scalable Matrix Engine), which is available to all four core types, ARM promises significant increases in AI calculations by the CPU: they should run faster by a factor of 3.7 on average. ARM claims to have reduced the latency of speech recognition with Whisper by a factor of 4.7, while LLM encoding with Gemma 3 now runs at 398 instead of 84 tokens per second. AI sound generation with Stable Audio is now completed in 9.7 instead of 27 seconds, according to the manufacturer.

SME2 is an optional extension of the CPU. ARM recommends installing one or two of these SME2 extensions on a high-end processor.

For the GPU, ARM is returning to the name Mali from the last used name Immortalis. With one to five GPU cores, it bears the name Mali G1-Pro, six to nine cores are called Mali G1-Premium and everything above Mali G1-Ultra. In addition to the larger number of cores, the G1-Ultra is characterized by a new ray tracing unit (RTUv2) in each core.

In ray tracing benchmarks, the Mali-G1 Ultra achieves results up to twice as high as its predecessor. It also performs AI tasks faster. ARM sees the biggest leap in this area in speech recognition, where the manufacturer claims an increase of 104 percent compared to the Immortalis-G925.

First chip from Mediatek?

The first chips with the new cores are expected before the end of this year. Mediatek has recently been ARM's preferred partner in the high-end segment. The presentation of the new Dimensity 9500, the successor to the Dimensity 9400+, could take place in the coming weeks. New SoCs from the XRing product line are also expected from Xiaomi. New Snapdragons are also on the horizon from Qualcomm, although they will use internally developed processing cores instead of ARM designs, at least in the upper class.

This year's ARM Tech Days focused exclusively on the Lumex platform. Under the name Niva, ARM is working for the first time on a core design explicitly conceived for PCs. The company remained silent on this at the event; ARM intends to announce more about Niva at a later date. The question of whether the C1 cores will also be used in Niva therefore remains unanswered for the time being.

Note: ARM covered the author's travel expenses and accommodation for the event.

(sht)