Intel Core i7-1355U vs AMD Ryzen 7 7840U

Intel Core i7-1355U

The Intel Core i7-1355U is a high-end mobile CPU for thin and light laptops based on the Alder Lake architecture (Raptor Lake-U / RPL-U series). It was announced in early 2023 and offers 2  performance cores (P-cores, Golden Cove architecture) and 8 efficient cores (E-cores, Gracemont architecture). The P-cores support Hyper-Threading leading to 12 supported threads when combined with the E-cores. The clock rate ranges from 1.7 to 5 GHz on the performance cluster and 1.2 to 3.7 GHz on the efficient cluster. The performance of the E-cores should be similar to old Skylake cores (compare to the Core i7-6700HQ). All cores can use up to 12 MB L3 cache. The CPU supports "Essentials" vPro management features. Compared to the P-series (28W) or H-series (45W), the 15W TDP may limit the sustained performance.

Performance

Thanks to the high clock speed, the Core i7-1355U should perform slightly better than the older core i7-1265U (up to 4.8 GHz). The faster i7 like the i7-1365U models offer only higher clock rates (and a faster iGPU).

Architecture

The integrated memory controller supports various memory types up to LPDDR5-6400. The Thread Director (in hardware) can support the operating system to decide which thread to use on the performance or efficient cores for the best performance. For AI tasks, the CPU also integrates GNA 3.0 and DL Boost (via AVX2). Quick Sync in version 8 is the same as in the Rocket Lake CPUs and supports MPEG-2, AVC, VC-1 decode, JPEG, VP8 decode, VP9, HEVC, and AV1 decode in hardware. The CPU still only supports PCIe 4.0 x8 for a GPU and two PCIe 4.0 x4 for SSDs.

The integrated graphics card is based on the Xe-architecture and offers all 96 EUs (Execution Units) operating at up to 1.3 GHz.

Power consumption

This Core i7 CPU is rated at a TDP of 15W (base power, PL1) and a maximum turbo power of 55W (PL2). The RPL-U processors are built in a further improved Intel 7 process (10nm SuperFin) that allows higher clock rates.

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.