Intel Core i7-1355U vs Intel Core 2 Duo P8400 vs Intel Core 2 Duo P8600

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 2 Duo P8400

Intel Core 2 Duo P8600

The Intel Core 2 Duo P8600 is a dual core processor for laptops. It features 2.4 GHz and a shared level 2 cache of 3 MB. Due to the smaller cache (Core 2 Duo T-Models got usually 6 MB at this clock rate), the TDP is only 25 Watt (instead of the 35 Watt of the T-models).

Due to the relatively high clock speed, modern games (in 2009) should not be limited by the CPU speed (in conjunction with a middle class graphics card). High end gamers should choose a higher clocked Dual Core instead (when using a high end GPU). Compared to the fastest Turion II Ultra M640, the P8600 should be still faster.

The P8600 uses a Penryn (Montevina Update) core that features 2 integer units, 1 floating point unit, 1 load unit, and 1 store unit in a 14-stages long pipeline. Due to the Wide Dynamic Execution Technology, the core is able to simultaneously execute up to four instructions.

The integrated Enhanced Speedstep is able to downclock the core dynamically as low as 1200 MHz to save power (in idle mode).

The Core 2 Duo P8600 can be used in a Socket P socket with 479 pins: Socket P / Micro Flip-Chip Pin Grid Array (Micro-FCPGA) requires 479-pin surface mount Zero Insertion Force (ZIF) socket (mPGA479M socket) or Micro Flip-Chip Ball Grid Array (Micro-FCBGA) for surface mount (479-ball)