AMD Ryzen 7 PRO 7840HS vs AMD Ryzen 5 8640HS

AMD Ryzen 7 PRO 7840HS

The AMD Ryzen 7 PRO 7840HS is a fast high-end laptop processor of the Phoenix series. It offers 8 cores (octa core) based on the Zen 4 architecture that supports hyperthreading (16 threads). The cores clock from 3.8 (base) up to 5.1 GHz (single core boost). The processor includes 8 MB L2 cache and 16 MB L3 cache.

Compared to the consumer Ryzen 7 7840HS, the PRO models offer additional security, manageability, and reliability features designed for professional users and workstation environments.

The performance of the R7 PRO 7840HS is only slightly below the fastest model, the R9 PRO 7940HS, as the clock speed difference is only minimal (e.g. -100 MHz / 2% slower single core boost). Therefore, the CPU should also perform slightly higher than the old top model Ryzen 9 6980HX (8 Zen 3 cores with up to 4.9 GHz) at 54W TDP and Ryzen 9 6980HS at 35W TDP. Compared to the higher end Dragon Range series, the 7840HS should be similar to the Ryzen 7 7745HX (also 8 Zen 4 cores, max 5.1 GHz, 55W TDP, 32 MB L3).

The chip integrates a modern and fast RDNA 3 graphics adapter (iGPU) called Radeon 780M with 12 CUs and up to 2.7 GHz clock speed. Furthermore, the Phoenix series include a video engine with AV1 de- and encoding, a new Xilinx FPGA based XDNA AI accelerator (Ryzen AI) that should be faster than the AI engine in the Apple M2 SOC and a dual-channel DDR5-5600 / LPDDR5x-7500 memory controller (with ECC support). The connectivity features includes 2 possible USB 4 (40 Gbps) ports and 20 PCIe 4.0 lanes for a GPU and SSDs.

The Phoenix series uses a single monolithic design (unlike the chiplet design of the 7045HX series) and is manufactured on the modern 4nm process at TSMC. The TDP can be configured between 35 and 45 Watt.

AMD Ryzen 5 8640HS

The Ryzen 5 8640HS is a mid-range, Hawk Point family processor that was unveiled in Q4 2023. The 8640HS isn't actually a new chip; instead, it's a rebadged Ryzen 5 7640U with a slightly higher wattage as well as higher clock speeds on the Ryzen AI NPU. The 8640HS has 6 SMT-enabled cores (12 threads) running at 3.5 GHz to 4.9 GHz. Those Zen 4 architecture cores are mated to the Radeon 760M integrated graphics adapter.

Architecture & Features

Hawk Point chips are powered by the Zen 4 architecture, much like Phoenix and Dragon Range family chips are. That's not to say there is no difference between the three. With Hawk Point, AMD is betting big on generative AI; these processors are set to deliver an up to 40% increase in generative AI performance over 7040 series APUs.

Unlike Zen 3, Zen 4 features AVX512 support and, thanks to a plethora of other improvements including larger caches/registers/buffers, is slated to deliver a double-digit IPC improvement over the former.

Elsewhere, the 8640HS has 16 MB of L3 cache and USB 4 support (therefore, Thunderbolt is supported as well). The chip is compatible with DDR5-5600 and LPDDR5x-7500 RAM which is still impressive as of late 2023.

A system powered by this Ryzen 5 will have access to twenty PCIe 4 lanes; this means a speedy enough NVMe SSD will be able to deliver speeds up to 7.8 GB/s.

Systems powered by this APU are expected to run 64-bit Windows 11, 64-bit Windows 10, or Linux. Like most laptop chips, the 8640HS is neither overclockable nor user-replaceable. It gets soldered to the motherboard for good (FP7, FP7r2, FP8 socket interfaces).

Performance

It's safe to expect the APU to be at least 15% faster than the Zen 3 Plus-powered Ryzen 5 6600U (6 cores, 12 threads, up to 4.5 GHz), as far as multi-thread performance is concerned.

Your mileage may vary depending on how high the CPU power limits are and how competent the cooling solution of your laptop is.

Graphics

The Radeon 760M has 8 CUs (512 shaders) running at up to 2,600 MHz. While not great for gaming (unless you are fine with resolutions such as 900p and low detail settings), the iGPU will let you use up to 4 monitors with resolutions as high as SUHD 4320p. It also HW-decodes and HW-encodes the most widely used video codecs including AV1, HEVC, AVC without breaking a sweat.

Power consumption

The 8640HS has a long-term power limit (default TDP) of 28 W that laptop makers are free to change to anything between 20 W and 30 W. Most companies will probably go for a higher value to get better performance. Either way, an active cooling solution is a must for any system powered by the chip.

Last but not the least, the 8640HS is manufactured on TSMC's 4 nm process for high, as of late 2023, energy efficiency.