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On 12th gen they disabled it on the P cores too even with E cores disabled with a microcode update. A lot of newer systems don't have access to the older micro
by monocasa 4y ago
On 12th gen they disabled it on the P cores too even with E cores disabled with a microcode update. A lot of newer systems don't have access to the older microcode, and microcode doesn't typically let you downgrade.
- wtallis 4y agoThere are workarounds for downgrading microcode, because the CPU itself doesn't actually have non-volatile storage for microcode updates and relies on the motherboard firmware to upload updates on each boot (and motherboard firmware can often be downgraded, possibly after changing a setting to allow that). Which is probably why Intel has changed to disabling AVX512 using fuses in more recently manufactured Alder Lake CPUs.
- monocasa 4y agoMy point with "a lot of newer systems" was that there are motherboards now that completely lack a version of their firmware with the microcode that allows avx-512. There's nothing to downgrade to without an exploit to allow making your own firmware images with mixed and matched components.