In brief: Intel 12th Gen Core desktop processors never officially supported AVX-512, but we have workarounds to enable this instruction set. However, new firmware releases might render these methods useless, as Intel is disabling AVX-512 support on Intel 12th-Gen Core CPUs at the BIOS level.
When Intel introduced the Intel 12th Gen Core/Alder Lake desktop processors to the public, the chipmaker never mentioned its products would support the AVX-512 instruction set. However, that didn't stop users from bypassing what turned out to be a soft lock. Users could enable AVX-512 on the P-cores via BIOS by disabling the E-cores on these processors.
Those running their current BIOS can still trigger the workaround, but new firmware might prevent you from using it down the line. A new report claims Intel will block AVX-512 support at a BIOS level, meaning that disabling the CPU's E-cores to enable support for AVX-512 won't work anymore.
Intel 12th-Gen Core processors will most likely employ the AVX2 instruction set as an alternative. Unlike AVX-512, Intel limits AVX2 to a maximum frequency of 5.1GHz regardless of power limits, BIOS settings, and thermal headroom, limiting the maximum performance it can offer. Intel never explained AVX2's limitations, but we believe they may be an attempt to prevent hardware degradation.
The reason for disabling the AVX-512 instruction set is still unclear, but a couple of reasons come to mind. The first would be efficiency, as it consumes more power than other AVX instruction sets. In specific use cases, the additional power consumption translates into noticeable performance gains, but the rarity we witness these improvements makes us believe it won't affect most users.
Another possible reason would be forcing those who benefit from AVX-512 to opt for workstation and server CPUs. The AVX-512 instruction set is still barely used in the mainstream market, but its implementation is much broader in productivity and enterprise applications.
Intel's removal of AVX-512 support wasn't enough to completely block users from using AVX-512 on Alder Lake desktop processors. By injecting microcode from older BIOS releases into a new one with AVX-512 disabled, users created a custom BIOS that still allows them to use the instruction set. As a custom BIOS, it's worth warning you about the risks that come with it, like bricking the motherboard. Install it at your own risk!