Intel Core i7-1355U vs Intel Core i5-1250P

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.

Intel Core i5-1250P

The Intel Core i5-1250P is a mid-range Alder Lake-P family SoC designed for use in ultra-light, ultra-thin (yet actively cooled) laptops. It was announced in early 2022 and it has 4 performance cores, as opposed to the 6 cores of the top-of-the-line i7-1280P (P-cores, Golden Cove architecture) mated to 8 efficient cores (E-cores, Gracemont architecture). The i5's P-cores are Hyper-Threading-enabled for a total of 16 threads when combined with its E-cores. The clock speeds range from 1.7 GHz to 4.4 GHz for the performance cluster and 1.2 GHz to 3.3 GHz for the efficient cluster. The shortcomings of this processor as compared with the slightly faster Core i5-1260P include the smaller L3 cache, slower iGPU model, lower clock speeds. Full vPro feature set is enabled in the case of this i5, though ("Enterprise" tier, allowing for remote device management).

Architecture

The i5 is a continuation of Intel's efforts to use the ARM-developed big.LITTLE technology for its own benefit. A single "little" Alder Lake core is supposed to be as fast as a Skylake core (as found in the venerable Core i7-6700HQ among other options) which is six years old at this point. All of Core i5-1250P's CPU cores enjoy access to 12 MB of L3 cache. The integrated memory controller supports various memory types up to LPDDR5-5200, DDR5-4800, LPDDR4x-4267 or DDR4-3200; Intel recommends using no more than 64 GB, for reference. Just like the other 12th Gen Intel Core processors, this Core i5 comes with the Thread Director which is a new functionality designed to help Windows 11 decide which cores to use for what workload for best performance and efficiency possible. Hardware acceleration of AI algorithms is supported via GNA 3.0 and DL Boost (via AVX2). The alluringly fast PCI-Express 5.0 spec has not found its way into Alder Lake P processors, so users will have to be content with PCI-Express 4.0 for the time being. Four PCI-Express 4 lanes allow for a read/write rate of up to 7.9 GB/s, provided a suitably fast NVMe SSD is used.

Please note this is not a user-replaceable CPU. It gets permanently soldered on to the motherboard (FCBGA1744 socket interface).

Performance

The average 1250P in our database nearly matches the Ryzen 5 5500U and the Ryzen 5 PRO 6650U in multi-thread performance, trailing behind the Core i5-1240P just slightly. This is a great CPU for nearly all tasks imaginable, as long as one does not expect it to be as fast as the mighty Core i7-12700H.

Your mileage may vary depending on how high the Power Limits are and how competent the cooling solution of your system is. The latter is really important as a single Golden Cove core can eat more than 20 W when under heavy load.

Graphics

The built-in graphics adapter in the form of the 80 EU Iris Xe running at up to 1.4 GHz has seen little change from what was built into certain 11th Gen Tiger Lake UP3 processors, like a Core i5-1135G7, which is hardly a downside as this iGPU is loaded with modern features, AV1 video decoding capability and SUHD 4320p monitor support included. The Xe isn't a stranger to a bit of casual gaming; that said, your mileage may vary depending on how high the Power Limits are and how capable the cooling solution of a laptop is. Expect something close to NVIDIA's MX250 or in other words, acceptable framerates in most games when playing at 1080p / Low settings. Fast RAM is a prerequisite for decent performance as the Xe has to make do with no dedicated video memory.

Power consumption

The i5's base power consumption (also known as the default TDP or Power Limit 1) is 28 W; its maximum Turbo power consumption (also known as the PL2) is not supposed to exceed 64 W. As for the "Minimum Assured" power consumption, Intel's guidelines mention 20 W. All in all, an active cooling solution is a must for a CPU like this.

The i5-1250P is built with Intel's fourth-gen 10 nm manufacturing process marketed as Intel 7 for decent, as of late 2022, energy efficiency. Despite that, the i5 is more power-hungry than certain 7 nm U-class AMD Ryzen 5000 chips delivering similar, or even higher, performance.