AMD Ryzen 7 7800X3D vs Intel Core i7-1255U

AMD Ryzen 7 7800X3D

The AMD Ryzen 7 7800X3D is a high-end desktop processor from the Raphael series with 8 Zen 4 cores and SMT (Simultaneous Multithreading), allowing it to handle up to 16 threads simultaneously. After its announcement in January 2023 at CES in Las Vegas, it was launched in April 2023. Following the launch of the two top models, the AMD Ryzen 9 7900X3D and the AMD Ryzen 9 7950X3D, the third model was introduced, which offers significantly more gaming performance with the 3D V-Cache.

The CPU cores have a base clock of 4.2 GHz and can be boosted up to 5 GHz (single-core turbo). The AMD Ryzen 7 7800X3D features a CCD with 8 cores, which includes the fast 3D V-Cache. This differs significantly from the two Ryzen 9 models, as they have two CCDs, but only one of them can utilize the 3D V-Cache.

The performance of the AMD Ryzen 7 7800X3D is consistently good, although its multi-threaded performance suffers a bit due to the eight native compute cores. However, the real strength of the AMD Ryzen 7 7800X3D lies in gaming performance, where it excels. In tests, we see consistently high gaming performance, even surpassing that of an Intel Core i9-13900K.

In terms of power consumption, the AMD Ryzen 7 7800X3D aligns with the other two models featuring 3D V-Cache, making the 8-core processor extremely power-efficient. In numbers, this means that the AMD Ryzen 7 7800X3D is specified with a TDP of up to 120 watts. The PPT (Package Power Tracking) is also rated up to 162 watts. For comparison, an AMD Ryzen 9 7950X is specified with 170 watts (TDP) or 230 watts (PPT).

Intel Core i7-1255U

The Intel Core i7-1255U is a high-end mobile CPU for thin and light laptops based on the Alder Lake architecture. It was announced in early 2022 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 4.7 GHz on the performance cluster and 1.2 to 3.5 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. Compared to the i7-1265U (fastest U-series CPU at launch), the 1255 offers 100 MHz lower clocked CPU cores and only "Essentials" vPro management features. Compared to the P-series (28W) or H-series (45W), the 15W TDP may limit the sustained performance.

Performance

The average 1255U in our database is in the same league as the Ryzen 5 5600U, as far as multi-thread benchmark scores are concerned. Which is nothing to be ashamed of, as of mid 2023.

Thanks to its decent cooling solution and a long-term CPU power limit of 28 W, the Spectre x360 13.5 14t-ef000 is among the fastest laptops built around the 1255U that we know of. It can be 20% faster in CPU-bound workloads than the slowest system featuring the same chip in our database, as of August 2023.

Architecture

The integrated memory controller supports various memory types up to DDR5-4800, DDR4-3200, LPDDR5-5200, and LPDDR4x-4267. 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 only supports PCIe 4.0 (x8 for a GPU and two x4 for SSDs).

The integrated graphics card is based on the Xe-architecture and offers all 96 EUs (Execution Units) operating at up to 1.25 GHz.

Power consumption

This Core i7 has a "minimum assured" power consumption of 12 W. Its Base power consumption sits at 15 W and its maximum Intel-recommended Turbo power consumption isn't supposed to exceed 55 W. All those values are too high to allow for pasisvely cooled designs.

Last but not the least, Core i7-1255U is built with Intel's fourth-gen 10 nm process marketed as Intel 7 for decent, as of late 2022, energy efficiency.