Can I downgrade my microcode enough so that my CPU won't work anymore?

Title pretty much says it all, I want to downgrade my microcode so that I can avoid some mitigations that slow down my PC. I have an I3-9100F and a Gigabyte b360m h. My question is, if I replace the microcodes with, let’s say, the ones before meltdown and spectre (afaik it is 70 on U0 stepping), will it still work with my CPU? Does ME, or the bios version have anything to do with microcodes(as in, if my bios is way too new or my ME, can this brick my motherboard?) Also, can a microcode be that old so that newer CPUs(such as the 9th gen) won’t be supported(bare in mind that on Gigabyte’s website it says that my CPU became supported later on, on version F12)?

F3 (2018-07) version says " 1. Bootable with Intel 9000 CPU"
as you said, for 9100 is stated F12… so a dilema here from Gigabyte??? Ask them…

906EB Coffee Lake-S (B0)
cpu906EB _plat02_ver00000072 _2017-09-20_PRD_A08C2841.bin
[OFFER] Intel CPU Microcode Archives - Special Topics / CPU Microcodes - Win-Raid Forum (
Replace it in F3 or F12… will it work in F3, same dilema…

Now once and for all… all mods have their RISKS, so NEVER ask if it breaks or not cause no one can assure you, a fail safe sucessufull operation in mods.

Users want this and that and so on, but have afraid and dont want to break their system… that’s not viable in mods scenarios… take the risks or NOT, simple as that.

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@andrei1058 There are two revisions of the 9100F;
CPUID 906EA = U0 Revision = S-spec SRF6N
CPUID 906EB = B0 Revision = S-spec SRF7W

There are microcodes for both of these CPU in all BIOS from F1 to F15, however the 9000 series CPU’s only received support through an Intel ME Firmware update (i.e must be updated with ME FW version or higher).

BIOS F1 to F11 ony have ME v12.0.3.xxxx (or lower) and do not support 9000 series CPU.
BIOS F12 and later have ME v12.0.22.1310 (or higher)

I would suggest using a modified F15, F15b or F13 BIOS with downgraded microcodes.

Note that F15 is a capsule BIOS that has extra security added which stops you downgrading to earlier BIOS using either Qflash or EFIflash. Fortunately it easy to downgrade BIOS using Intel’s Flash Programming Tool (v12) on this board as you don’t have to worry about erasing the MAC address because it has a Realtek ethernet adapter (rather than Intel).

Note that you will also need to delete/rename the file ‘mcupdate_GenuineIntel.dll’ on a Windows 10/11 system or it will override the older microcode in BIOS when Windows starts.

Note that this file will be restored if you run the system file check “sfc /scannow” or if a Windows update reinstates mcupdate_GenuineIntel.dll.

If you are ok with messing with the mcupdate_GenuineIntel.dll file then I can make a BIOS for you with the microcode of your choosing - just let know which BIOS you want modified.


Oh, thank you so much! I was sure about the ME part, and I already modded a F15 bios with the F12 microcode, and it works a bit better(about 3-5% more Cinebench points and less stutters, WAY LESS STUTTERS, they just killed this CPU with those updates I swear, but it is understandable as it this more secure). Anyway, was not so sure about the microcode part, so thanks for confirming it. I was testing literally method on the web on how to load an older than the motherboard’s microcode without modding it(so I can test if it works without bricking mine), and I couldn’t do it through Linux, neither with Intel Microcode BootLoader, as they would take the one that was more recent between the bios and their variant. I will try flashing one rn with the F1 microcode and keep you up with the result. Thanks so much!
UPDATE2: Revision 84(from F1) works so great, another 2% consistent score increase in Cinebench(is not much, but my 0.1% went up by about 6% in other benchmark, and this is not placebo as I have also tested this with both variants for about 5 tries alternating between them, so the improvement is there for sure). Still, my Revision 70 dilemma stays, is it compatible with my i3-9100F?

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Update: F1 is using revision 84, but as mentioned in my post, I would like to have revision 70(cpu906EA_plat22_ver00000070_2017-08-23_PRD_711B866C.bin), is this one also compatible with my i3-9100F?

@andrei1058 Hi, looks like you’ve been busy!

Yes you can use 70 and that is the one I would recommend as it is pre-spectre.

You can use any microcode revision for your specific CPUID, so if you have 906EA you can use any microcode you want - even going back as far as revision 5C from 2017.