The Intel Core i7-8665U is a power efficient quad-core SoC for notebooks and Ultrabooks based on the Whiskey Lake generation that was announced in April 2019 as part of two vPro enabled WHL-U processors. Compared to the similar named Kaby Lake-R processors (e.g. Core i7-8550U), the Whiskey Lake CPUs are now produced in a further improved 14nm process (14nm++) and offer higher clock speeds. The architecture and features are the same. The i7-8665U offers e.g. high Turbo clock speeds of 4,8 GHz (versus 4 GHz of the i7-8550U) for a single core. The integrated GPU is still named Intel UHD Graphics 620 and the dual-channel memory controller still supports the same RAM speeds as Kaby-Lake-R (DDR4-2400 / LPDDR3-2133). Compared to the slower Core i5-8265U and i3-8145U, the i7 should support Thermal Velocity Boost (like the Core i7-8565U, the predecessor).
The Whiskey Lake SoCs are used with a new PCH produced in 14nm that supports USB 3.1 Gen 2 (10 Gbps) and CNVi WiFi/BT parts.
Intel basically uses the same micro architecture compared to Skylake and Kaby Lake, so the per-MHz performance does not differ. That means Whiskey Lake is a Kaby Lake chip manufactured in the improved 14nm++ process.
The performance of the i7-8665U depends on the cooling solution of the laptop and the defined TDP limits for short and long term performance. We already saw big differences for Kaby Lake-R (e.g., i7-8550U benchmarks), especially for long term (sustained) performance. Therefore, it will be interesting to see how the additionalTurbo clock speed can be made use of. Due to the 200 MHz higher Turbo Boost, the 8665U should outperform the i7-8565U (see for benchmarks).
Contrary to Skylake, Kaby Lake and Whiskey 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.
The chip is manufactured in a further improved 14nm process with FinFET transistors (14nm++), the same as the 8th Gen Coffee 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.