Intel Core i7-1255U vs Intel Core i3-N300

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.

Intel Core i3-N300

The Intel Core i3-N305 is an entry-level mobile CPU for thin and light laptops from the Alder Lake-N series. It was announced in early 2023 and offers no performance cores and 8 efficient cores (E-cores, Gracemont architecture). The chip does not support HyperThreading and clocks with up to 3.8 GHz (single core, 3 GHz all core Turbo). 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 6 MB L3-cache. 

Performance

The performance depends on the cooling and TDP settings and should be somewhere similar to the old  Alder Lake Pentium 8500 (1 performance core, 4 efficiency cores, max. 4.4 GHz and 8 MB L3-cache). The multi-threaded performance should be quite good with the 8 cores but will suffer due to the low TDP. Single thread performance will suffer due to the missing P-cores and relatively low boost clock speeds.

Features

The Alder Lake-N chips only support single channel memory with up to DDR5-4800, DDR4-3200 or LPDDR5-4800. The chip also supports Quick Sync and AV1 decoding (most likely same engine as in Alder Lake). Furthermore, Wi-Fi 6E and Bluetooth 5.2 are partly integrated (but no Thunderbolt). External chips can be connected via PCIe Gen3 x9 (via the PCH).

The integrated graphics adapter is based on the Xe-architecture and offersall 32 EUs (Execution Units) operating at up to 1.25 GHz. In addition to the single channel memory, the gaming performance is very limited of the iGPU.

Power consumption

The i3 has a base power consumption of 7 W and is therefore even suited for fanless cooling. The CPU is built with a further improved 10nm SuperFin process at Intel (called Intel 7).