What the RTX Spark CPU Is and Why It Looks Like a Smartphone Chip
The RTX Spark CPU is NVIDIA’s custom 20-core Grace processor for Windows PCs that combines smartphone-style Arm cores with desktop-oriented power delivery, frequencies, and memory to create a hybrid architecture tuned for AI, gaming, and everyday workloads. Built into the broader RTX Spark platform, this Grace CPU sits alongside a Blackwell-based RTX GPU and up to 128GB of unified LPDDR5X memory, turning the whole package into a single system-on-chip for laptops and compact desktops. The heart of the design is a 10+10 core layout: ten Cortex-X925 performance cores paired with ten Cortex-A725 efficiency cores, a pattern long used in flagship phones. In RTX Spark, that familiar layout is scaled up, clocked higher, and backed by stronger cooling and power budgets, so it can aim at traditional x86 laptop performance while keeping power draw closer to mobile silicon than to legacy desktop processors.
Inside the 10 Cortex-X925 + 10 Cortex-A725 Hybrid Core Architecture
RTX Spark’s Grace CPU uses a hybrid core architecture that mirrors modern smartphone chipsets but targets desktop-style multitasking. The ten Cortex-X925 performance cores are designed for heavy, bursty work such as gaming, code compilation, or AI processing, while the ten Cortex-A725 efficiency cores handle background tasks, video streaming, and light productivity at lower power. According to TechNetBooks, NVIDIA’s Grace CPU “contains ten high performance Cortex X925 cores, as well as ten low power Cortex A725 cores,” a layout inspired by MediaTek Dimensity SoCs. On PCs, this split allows the scheduler to push foreground threads onto the X925 cluster and park idle or low-priority tasks on A725, reducing wasted energy. The result is a desktop processor design that can scale from quiet, low-power operation to high sustained performance, depending on what the user is doing at any moment.
TSMC 3nm and MediaTek: Mobile Manufacturing Meets Desktop Workloads
The RTX Spark CPU is manufactured on TSMC’s 3nm process, a node widely associated with smartphone flagships, but here adapted to sustain higher power envelopes in laptops and small desktops. MediaTek’s role goes far beyond licensing Arm cores. TechNetBooks reports that MediaTek engineered the custom memory controller for the unified LPDDR5X architecture, the power management circuitry, and the wireless subsystems, bringing years of mobile power-efficiency experience into a PC platform. Unified memory is central: instead of splitting system RAM and VRAM, RTX Spark connects the Grace CPU and Blackwell GPU to up to 128GB of shared LPDDR5X via a high-speed NVLink C2C interface rated around 600GB/s. This helps AI and GPU-heavy workloads move data without the overhead of separate memory pools, while the 3nm process and mobile-style power management keep thermals under control in 14mm-class notebook designs.
Custom Cortex-X925 and A725 Cores Tuned for PC, Not Phones
Although RTX Spark uses Cortex-X925 and Cortex-A725 cores that first appeared in MediaTek Dimensity mobile chips, NVIDIA did not drop in phone silicon unchanged. Die analysis referenced by Wccftech shows that the X925 cores in RTX Spark are smaller than those in the Dimensity 9400, yet adopt the power rail design used by the newer Dimensity 9500’s C1-Ultra cluster. This mix of traits is aimed at higher sustained frequencies and better power delivery for long PC workloads, such as multi-hour gaming or AI training sessions. Wccftech notes that “attributes from both the Dimensity 9400 and Dimensity 9500 were taken and applied to the RTX Spark to enable higher sustained frequencies.” Paired with a platform TDP that can reach around 110W in devices like the Surface Laptop Ultra, these tuned cores can run faster, longer, without hitting the thermal walls typical of phone-class SoCs.
What the Hybrid Grace CPU Means for Real-World PC Use
In daily use, RTX Spark’s hybrid 10+10 core design aims to blend the responsiveness of high-end phones with the flexibility of a desktop processor. Heavy, foreground workloads such as games, creative apps, and AI models run on the Cortex-X925 cluster and are backed by a Blackwell RTX GPU delivering up to 1 PFLOP of claimed AI performance. Meanwhile, the Cortex-A725 cores keep the system responsive while saving power during lighter activity, which should help RTX Spark laptops stay thin and battery-friendly without sacrificing burst performance. NVIDIA’s established software stack—CUDA, TensorRT, DLSS, Reflex, and ray tracing—sits on top, which is vital for an Arm-based Windows platform. If schedulers and thermal designs are well tuned, users can expect a PC that feels quick under load, stays efficient during idle time, and brings mobile-style silicon efficiency to mainstream Windows laptops and compact desktops.
