The support status for Windows 7 is complicated. To force people to "upgrade" to Windows 10, MS basically cut support early, and in an aggressive manner, by blocking updates from being installed on newer processors, and working with Intel to not provide Windows 7 drivers for newer processors. This means hardware with official driver support ended much earlier, compared to XP. Patching the OS might also be necessary.
Multiple posts on Zhihu reached mostly the same conclusions (in terms of generations) as I did. The differences are:
Comparison: 5950X>5800X3D>10980XE>9900KS>8086K
The big.LITTLE-like hybrid architecture used since Alder Lake (12th gen Intel Core) received limited support in Windows 10 and full support in Windows 11 (source). This effectively means a cut-off for Windows 8.1 and older, as they will not be running optimally. Therefore, I consider trying to run Windows 7 on 12th gen and later pointless.
The last generation of CPUs with official driver support is 10th gen Cascade Lake-X CPUs, the best of which is i9-10980XE. 11th gen has no X/Extreme CPUs. i9-10980XE outperforms i9-11900K.
The ASRock X299 OC Formula motherboard supports all LGA 2066 non-Xeon CPUs, which can be considered alternatives.
Some ASRock X299 motherboards like "Fatal1ty X299 Professional Gaming i9" and "X299 Killer SLI/ac" claim to support Windows 8.x, but the provided drivers are actually not for Windows 8.x. The chipset driver is compatible with Windows Server 2012 R2 though, which is based on Windows 8.1; maybe the driver can be installed with some modifications.
Microsoft's official supported processors list, both for Windows 7 and Windows 8.1, only lists up to 9980XE (probably because it's Skylake). I assume that means, if you use 9980XE, you wouldn't need to patch Windows Update. However since 10980XE shares a chipset, it should work.
Comet Lake-S (best: i9-10900K, socket: LGA 1200, chipset: Z490/Z590) doesn't support Windows 7. Coffee Lake-R and Coffee Lake-S (best: i9-9900KS / i7-8086K, socket: LGA 1151-2) does support Windows 7 but officially only with the B365 chipset; unofficially Z370 can work, but not Z390.
TL;DR: Download chipset and SATA drivers for Win10. The Win10 chipset driver officially works on Win7, while the SATA driver can still be manually installed from Device Manager. Inject USB 3.0 and NVMe drivers into installation media. Integrated GPU is not supported, but a dedicated GPU is better anyway.
The network adapter, I219-V, has a Windows 8.x driver. The audio driver is provided by Asus. The "Windows 10" chipset driver also officially supports Windows 8. The SATA driver should be usable on Windows 8, since it's a "Windows 10" driver that also works on Windows 7. Not sure whether the USB 3 and NVMe drivers would work though; modified drivers might be needed.
Microsoft's official supported processors list, both for Windows 7 and Windows 8.1, only lists up to 6700K. This lines up with Microsoft's statement that Skylake would be the last microarchitecture supported.
The Z270 chipset is made for Kaby Lake (the next generation) but is backwards-compatible with Skylake. The Z170 chipset is made for Skylake but made compatible with Kaby Lake after an update. The difference is minimal. If a Z170 motherboard is desired, Gigabyte GA-Z170X-Gaming 7 is nice.
Kaby Lake (best: i7-7700K) should also be usable.
From a now-locked forum:
Officially, AMD's HEDT platforms - the Threadripper - only supports Windows 10 and up. Unofficially, the modded drivers by canonkong work with even Threadripper 7960X (Zen 4, latest generation as of July 2025). (source)
AMD didn't follow Intel, and kept using traditional designs. As a result, the official driver support cut-off is way more reasonable.
The last generation of chipsets to have official Windows 7 drivers is X470/B450. The best CPU in this generation is 5950X.
However, many people on Reddit say that 5950X actually performs worse than 5800X3D when gaming, despite having higher benchmark scores; 5950X is better-suited for productivity workloads such as video editing. In addition, a new model, 5700X3D, was released in 2024, that only performs slightly worse than 5800X3D but can be bought for "about half the price". 5900XT, another model released in 2024, doesn't make sense.
According to GamersNexus, X470 is basically the same board as X370, so X370 can be considered a cheaper alternative.
Here's a report of the 5950X working on Windows 7.
Microsoft's official supported processors list only lists APUs, so it can be ignored.
Modded drivers (ACPI, USB3) by canonkong are available for X570/B550 and X670/B670, allowing 7950X to be used. Wi-Fi still can't be used though.
According to another Reddit post, 7950X3D "[has] issues reaching their potential because a chipset driver is necessary to get full performance".
The RX 6950 XT is between the RTX 3090 and the RTX 3090 Ti in performance, but is cheaper than the RTX 3090.