An overclocker has found a way to quickly and easily distinguish between Intel's 12th Generation Core 'Alder Lake' processors that have AVX-512 support disabled by microcode and can be re-enabled with an appropriate BIOS, as well as Alder Lake chips that have their AVX-512 unit fused off physically. All you have to do is to look for a CPU with an old Intel logotype on its integrated heat spreader (IHS), according to Overclocker Luumi (via VideoCardz).
When Intel was getting ready to launch its latest 12th Generation Core 'Alder Lake' CPUs last year, it told software developers that its Golden Cove (P)erformance cores fully supported AVX-512 instructions (just like cores inside previous-generation CPUs), but Gracemont (E)fficiency cores did not. But as the launch was nearing, the company decided to disable AVX-512 support on P-cores to ensure overall stability just months before launch, which is why loads of initial LGA1700 motherboards came with microcode with enabled AVX-512 support. It caused a lot of confusion.
To disable AVX-512 for sure, Intel released a new reference UEFI BIOS version (which serves as a foundation for UEFI versions shipped by motherboard makers) that turned technology off, but then some mainboard makers released UEFI BIOSes that re-enabled AVX-512. Eventually, to ensure that the appropriate hardware unit cannot be activated, Intel began to physically fuse off its AVX-512 module from Alder Lakes.
But there are loads of 12th Generation Core processors that have their AVX-512 unit intact and which can be activated. Luumi has discovered that these 'lucky' Alder Lake CPUs with AVX-512 have Intel's ancient round 'Intel Inside'-like circle logotype on the upper left side of their IHS. By contrast, the 'unlucky' Alder Lake chips with AVX-512 fused off carry Intel's modern square logotype on the same part of their IHS.
"Seems that nearly all 2022 batched Alder Lake CPUs have AVX-512 disabled, so you are better off hunting a 2021 batch CPU," Luumi wrote. "Luckily for us Intel left a mark to determine does the CPU support AVX-512 or not, by looking at the IHS. Every CPU that has a halo/circle marking on top of the word Intel on the IHS will have AVX-512 support, and all rectangle/square ish marking CPUs will have it disabled by Intel. So at least with the Pentiums and other lower end models you can just walk around in a store and look at the processor's IHS from the small peek window and determine if it has AVX-512 or not."
To activate AVX-512, you will still need an appropriate UEFI BIOS version, and an eventual update will almost certainly disable the technology, but if you need AVX-512 here and now and no firmware updates are planned, this may not be an issue.
AVX-512 instructions are required for encoding/decoding, cryptography, scientific, and various professional applications. Gamers and users of regular applications hardly need AVX-512, but if you do, re-enabling it makes a lot of sense.