Intel Core i7-3520M vs Intel Celeron 3865U vs Intel Core i7-3635QM

Intel Core i7-3520M

The Intel Core i7-3520M is the fastest dual-core processor for laptops based on the Ivy Bridge architecture at the time of introduction in Q2 2012. Due to Hyperthreading, the two cores can handle up to four threads in parallel leading to better utilization of the CPU. Each core offers a base speed of 2.9 GHz but can dynamically increase clock rates with Turbo Boost up to 3.4 GHz (for 2 active cores) and 3.6 GHz (for 1 active core). As its Sandy-Bridge-based predecessor Core i7-2640M, it offers a 4 MB L3-Cache.

Ivy Bridge is an enhanced die shrink of the Sandy Bridge architecture with improvements on both GPU and CPU performance. The CPUs are produced in 22nm (versus 32nm Sandy Bridge CPUs) and are the first to introduce 3D transistors for increased energy efficiency when compared to similarly clocked Sandy Bridge processors. Other new features are integrated PCI Express 3.0 and  DDR3(L)-1600 support.

The performance of the Core i7-3520M is slightly above a similarly clocked Sandy Bridge processor due to the architectural improvements. As a result, overall performance is about 5 - 10 % above the old i7-2640M (see benchmarks below).

The integrated Intel HD Graphics 4000 offers 16 Execution Units (EUs) clocked at 650 MHz up to 1250 MHz with Turbo Boost, making it one of the fastest variants.

Just like most other Ivy Bridge dual-cores, the i7-3520M is rated at a TDP of 35 W. Therefore, even smaller laptops can use the Core i7.

Intel Celeron 3865U

The Intel Celeron 3865U is an ULV (ultra low voltage) dual-core SoC based on the Kaby-Lake architecture and has been launched in the first quarter of 2017. The CPU can be found in ultrabooks as well as normal notebooks. In addition to two CPU cores clocked at 1.8 GHz (no Turbo Boost, no HyperThreading), the chip also integrates an HD Graphics 610 GPU and a dual-channel DDR4-2133/DDR3L-1600 memory controller. The SoC is manufactured using a 14 nm process with FinFET transistors.

Architecture

Intel basically uses the same micro architecture compared to Skylake, so the per-MHz performance does not differ. The manufacturer only reworked the Speed Shift technology for faster dynamic adjustments of voltages and clocks, and the improved 14nm process allows much higher frequencies combined with better efficiency than before.

Performance

Due to the missing Turbo Boost and the low clock speeds, especially the single thread performance is very limited which results in a lower performance even for lower demanding tasks. The performance should be noticeably slower than the Celeron 3965 which offers 400 MHz higher clocked CPU cores. Therefore, the CPU is only suited for entry level tasks like office, web surfing and multimedia.

Graphics

The integrated graphics unit called HD Graphics 610 (similar to the HD Graphics 510) represents the "GT1" version of the Kaby Lake GPU (Intel Gen. 9). Its 12 Execution Units, also called EUs, are clocked at 300 - 900 MHz and offer a performance somewhat below the older HD Graphics 4400. Only a few games of 2015 can be played smoothly in lowest settings.

Power Consumption

Specified at a TDP of 15 W (including CPU, GPU and memory controller), the CPU is best suited for small notebooks and ultrabooks (11-inches and above). Optionally, the TDP can be lowered to 10 watts (cTDP down), reducing both heat dissipation and performance and allowing even more compact designs.

Intel Core i7-3635QM

The Intel Core i7-3635QM is a fast quad-core processor for laptops based on the Ivy Bridge architecture. Due to Hyperthreading, the four cores can handle up to eight threads in parallel leading to better utilization of the CPU. Each core offers a base speed of 2.4 GHz but can dynamically increase clock rates with Turbo Boost up to 3.2 GHz (for 4 active cores), 3.3 GHz (for 2 active cores) and 3.4 GHz (for 1 active core). In contrast to the 3630QM, the 3635QM has a different package (BGA) and a slightly higher GPU clock.

Ivy Bridge is an enhanced die shrink of the Sandy Bridge architecture with improvements on both GPU and CPU performance. The CPUs are produced in 22nm (versus 32nm Sandy Bridge CPUs) and are the first to introduce 3D transistors for increased energy efficiency when compared to similarly clocked Sandy Bridge processors. Other new features are integrated PCI Express 3.0 and  DDR3(L)-1600 support.

The performance of the Core i7-3635QM is slightly above a similarly clocked Sandy Bridge processor due to slight architectural improvements. As a result, overall performance is similar to the fastest Sandy Bridge model, the Core i7-2960XM.

The integrated Intel HD Graphics 4000 offers 16 Execution Units (EUs) clocked at 650 MHz up to 1200 MHz with Turbo Boost, making it one of the faster variants.

As with most quad-core Ivy Bridge models, the Core i7-3635QM is specified at a TDP of 45 Watts including graphics card and memory controller. Therefore, the CPU is well-suited for laptops 15-inches or greater.