Intel Core i7-8650U vs Intel Core i7-6650U vs Intel Core i7-6820HK

Intel Core i7-8650U

The Intel Core i7-8650U is a power efficient quad-core SoC for notebooks and Ultrabooks based on the Kaby Lake Refresh generation and was announced in August 2017. Contrary to its direct predecessor the Core i7-7600U, which were still dual-cores, the i7-8650U is equipped with four cores but at a lower base frequency of 1.9 GHz. The Turbo Boost can go up to 4,2 GHz and therefore also offer good short term single core speeds. The GPU is now named Intel UHD Graphics 620 but otherwise identical to the Intel HD Graphics 620. The integrated memory controller supports DDR4-2400 / LPDDR3-2133 and dual channel memory.

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

According to Intel, the new quad core models are up to 40% faster than their dual core predecessors. Due to the reduced TDP and the same 14nm+ process, the long term performance and throttling behaviour will be interesting and depending on the laptop design. Therefore, the older 35 Watt quad-core models should be faster in applications that demand longer CPU loads. The performance however is highly depending on the TDP settings and cooling solution of the laptop. Especially, longer loads will show varying results in different laptops.

Graphics

The integrated Intel UHD Graphics 620 (Intel Gen 9.5) is untouched from the 8th Gen Kaby Lake chips. With fast dual-channel memory it can reach the performance of a dedicated GeForce 920M.

Contrary to Skylake, Kaby lake now also supports H.265/HEVC Main 10 with a 10-bit color depth as well as Google's VP9 codec. The dual-core Kaby Lake processors announced in January should also support HDCP 2.2.

Power Consumption

The chip is manufactured in an improved 14nm process with FinFET transistors (14nm+), the same as the 7th Gen Kaby Lake processors. Intel still specifies the TDP with 15 Watts, which is typical for ULV chips. Depending on the usage scenario, the TDP can vary between 7.5 (cTDP Down) and 25 Watts.

Intel Core i7-6650U

The Intel Core i7-6650U is an ULV (ultra low voltage) dual-core SoC based on the Skylake architecture. In September 2015, it's the fastest CPU of the 15 W series (besides the i7-6600U) and can be found in ultrabooks as well as normal notebooks. In addition to two CPU cores with Hyper-Threading clocked at 2.2 - 3.4 GHz (2 cores: max. 3.2 GHz), the chip also integrates an Iris Graphics 540 GPU with 64 MB of dedicated eDRAM memory and a dual-channel DDR4-2133/DDR3L-1600 memory controller. The SoC is manufactured using a 14 nm process with FinFET transistors.

Architecture

Skylake replaces both Haswell and Broadwell and brings the same microarchitecture in every TDP class from 4.5 to 45 W. The extensive improvements of the Skylake design include increased out-of-order buffers, optimized prefetching and branch prediction as well as additional performance gains through Hyper-Threading. Overall, however, performance per clock has been increased by only 5 to 10 percent (compared to Haswell) respectively under 5 percent (compard to Broadwell), which is quite modest for a new architecture ("Tock").

Furthermore, the organisation of the eDRAM cache has been modified. Instead of acting like a victim cache, which has to be adressed via the L3/LLC, the eDRAM can now be adressed directly by programms just like the main memory. The size is still 128 MB for the quad-core models (4C + GT4e), while the dual-core chips (2C + GT3e) only offer 64 MB.

Performance

According to the specified clock rates and the improved architecture, the Core i7-6650U should perform similar to a Core i5-4310M (Haswell, 37 W) and is one of the fastest ULV dual-cores as of late 2015. Thus, the CPU has sufficient power for office and multimedia purposes as well as more demanding applications and multitasking.

Graphics

The integrated graphics unit called Iris Graphics 540 represents the "GT3e" version of the Skylake GPU (Intel Gen. 9). The 48 Execution Units, also called EUs, are clocked at 300 - 1050 MHz and offer (thanks to the fast eDRAM cache) a performance sligthly above a dedicated GeForce 920M. Games of 2015 can thus be played smoothly in low or medium settings. For more information about performance and features, check our page for the Iris Graphics 540.

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 9.5 watts (cTDP down), reducing both heat dissipation and performance and allowing even more compact designs.

Intel Core i7-6820HK

The Intel Core i7-6820HK is a quad-core processor based on the Skylake architecture, that has been launched in September 2015. In addition to four CPU cores with Hyper-Threading clocked at 2.7 - 3.6 GHz (4 cores: max. 3.2 GHz, 2 cores: max. 3.4 GHz), the chip also integrates an HD Graphics 530 GPU and a dual-channel DDR4-2133/DDR3L-1600 memory controller. The CPU is manufactured using a 14 nm process with FinFET transistors.

Currently, the i7-6820HK is the only Skylake chip with an unlocked multiplier for easy overclocking (similar to previous Extreme Editions).

Architecture

Skylake replaces both Haswell and Broadwell and brings the same microarchitecture in every TDP class from 4.5 to 45 W. The extensive improvements of the Skylake design include increased out-of-order buffers, optimized prefetching and branch prediction as well as additional performance gains through Hyper-Threading. Overall, however, performance per clock has been increased by only 5 to 10 percent (compared to Haswell) respectively under 5 percent (compard to Broadwell), which is quite modest for a new architecture ("Tock").

Performance

Tanks to the improved architecture, the Core i7-6820HK performs roughly on par with the former Core i7-4900MQ (Haswell) or the Core i7-5700HQ (Broadwell). Under long-lasting full load, the Skylake chip will take the lead over most of its Haswell-based predecessors, as the advanced 14 nm process leads to a higher energy efficiency and reduces throttling. If the 6820HK is overclocked (we've tested up to 4.0 GHz on all 4 cores), the performance will be even better.

Even the most demanding applications and excessive multitasking are handled easily.

Graphics

The integrated graphics unit called HD Graphics 530 represents the "GT2" version of the Skylake GPU (Intel Gen. 9). The 24 Execution Units, also called EUs, are clocked at 350 - 1050 MHz and offer a performance about 20 percent above the old HD Graphics 4600. Games of 2015 can thus be played smoothly in low or medium settings. For more information about performance and features, check our page for the HD Graphics 530.

Power Consumption

Specified at a TDP of 45 W (including CPU, GPU and memory controller), the CPU is best suited for bigger notebooks 15-inches in size and above. Optionally, the TDP can be lowered to 35 watts (cTDP down), reducing both heat dissipation and performance.