The AMD A9-9425 is an entry-level chip from the Stoney-Ridge APU series for notebooks (7th APU generation), which was announced mid 2018. Compared to the one year older A9-9420, the 9425 has a 100 MHz higher CPU clock speed (base and boost) as well as a marginally faster iGPU. It integrates two CPU cores (one Excavator module with 2 integer and on FP unit) clocked at 3.1 GHz to 3.7 GHz. It also includes a Radeon R5 GPU with 192 shaders at up to 900 MHz as well as a single-channel DDR4-2133 memory controller, H.265 video decoder and chipset with all I/O ports.
Stoney Ridge is the successor of the Carrizo architecture and the design is almost identical. Thanks to optimized manufacturing processes and more aggressive Boost behavior, however, the clocks are a bit higher at the same power consumption. The memory controller now also supports DDR4-RAM, in this case up to 2133 MHz. Stoney Ridge is the designation for the smaller dual-core and single-core chip, while Bristol Ridge is the bigger quad-core chip with dual-channel memory controller. More technical details are available in the following articles:
Thanks to the high maximum clock of up to 3.7 GHz, the single-core performance is adequate. The multi-core performance on the other hand is limited by the single module and therefore only positioned of the entry level of 2018 CPUs. That means the A9 is most suited for low demanding applications.
The TDP can be configured between 10-15 Watts, so there can be big performance differences under sustained workloads.
The integrated Radeon R5 (Stoney Ridge) GPU has 192 active shader units (3 compute cores) clocked at up to 900 MHz. More details about the GPU are available in the linked articles above.
AMD specifies the TDP of the A9-9425 with 15 Watts, but it can be configured between 10-15 Watts. This means the CPU is a good choice for thin and light notebooks, but also 15-inch devices with better cooling capabilities.