AMD Ryzen 7 7840U vs AMD Ryzen 7 7840S

AMD Ryzen 7 7840U

The Ryzen 7 7840U is a powerful laptop processor (APU) of the Phoenix product family. Its eight Zen 4 cores run at 3.3 GHz to 5.1 GHz and are SMT-enabled for a total of 16 processing threads. The great Radeon 780M is responsible for 3D processing and similar duties; the 7840U also features Ryzen AI which is AMD's answer to Intel's GNA and DL Boost.

Architecture & Features

Phoenix family chips are powered by the Zen 4 architecture, much like Dragon Range family chips are. The latter however lacks hardware AI workload acceleration capabilities that Phoenix has.

More importantly, Zen 4 introduces some rather solid AVX512 support (which Zen 3 chips did not have) and, thanks to a plethora of other improvements including larger caches/registers/buffers across the board, is set to bring a double-digit IPC improvement.

Elsewhere, the 7840U has 16 MB of L3 cache and support for super-fast DDR5-5600 and LPDDR5x-7500 RAM. The chip is compatible with USB 4 and thus with Thunderbolt. It comes with 20 PCIe 4 lanes for NVMe SSD speeds of up to 7.8 GB/s.

Systems built around the 7840U are designed to run 64-bit Windows 11, 64-bit Windows 10, or Linux. Please note that this processor is not overclockable and neither is it user-replaceable. It gets soldered down for good instead (FP7, FP7r2, FP8 socket interfaces).

Performance

The average 7840U in our extensive database is about as fast as the Core i7-12650H, as far as multi-thread benchmark scores are concerned. This means the Ryzen 7 APU packs quite a wallop, as of mid 2023.

Thanks to its decent cooling solution and a long-term CPU power limit of 35 W, the Framework Laptop 13.5 is among the fastest systems powered by the 7840U that we know of. It can be about 30% faster than the slowest system featuring the same chip in our database, as of December 2023.

Graphics

The Radeon 780M has 12 CUs (768 shaders) purring away at up to 2,700 MHz. This is exactly the right iGPU for people looking for a bit more horsepower than what Intel's aging Xe options can provide. The Radeon will let you use up to 4 monitors with resolutions as high as SUHD 4320p and it will also HW-decode and HW-encode the most widely used video codecs (including AV1, HEVC and AVC) without breaking a sweat. In terms of gaming, the thing is good enough for 1080p and medium-to-low settings, as of late 2023.

Your mileage may vary depending on how high the CPU power limits are, how competent the cooling solution of your system is, how fast the RAM of your system is (there is no dedicated VRAM here).

Power consumption

This Ryzen 7 series chip has a long-term power limit (default TDP) of 28 W. Laptop makers are free to change that value significantly, with values as low as 15 W and as high as 30 W greenlighted by AMD. Either way, an active cooling solution is a must for any system powered by this chip.

The 7840U is built with TSMC's 4 nm process for high, as of late 2023, energy efficiency.

AMD Ryzen 7 7840S

The AMD Ryzen 7 7840S 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. The processor is exclusively available in Lenovo laptops but the specs are similar to the regular Ryzen 7 7840HS.

The performance of the R7 7840S is only slightly below the fastest model, the R9 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 fasts RDNA 3 graphics card (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 in the modern 4nm process at TSMC. The TDP can be configured between 35 and 45 Watt.