Schmorp's POD Blog a.k.a. THE RANT
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This document was first published 2022-08-16 12:06:50, and last modified 2022-08-16 13:13:52.

ASRock B85M Pro3 All Core Sync non-K Overclock

Long time ago I bought a lowly ASRock B85-Pro3 board plus i3-4170 CPU for occasional multiplayer gaming (3.7GHz*2). Recently, my more capable TV with i5-4760S CPU died, and I thought to move the CPU (3.8GHz*4) to it - the problem: the BIOS had been upgraded to a version which no longer allows all core sync overclocking for either of these CPUs. Didn't matter for the 4170, but it did matter for the 4760, as that would downclock to 3.6GHz when just two cores were active - not much of an upgrade for gaming.

So I had to downgrade the BIOS to version 1.30, which still had the "Multicore Enhancement" option to enable non-K model overclocking. Unfortunately, I also had to downgrade the embedded CPU microcode, and no older BIOS had microcode embedded, so downgrading would not have restored non-K OC. Sometimes you can find modded BIOSes for this purpose on the net, but not for this board, so I had to patch the BIOS myself.

With the patched BIOS, I was able to successfully downgrade the microcode and the BIOS version simply by flashing both BIOS images in sequence. You are invited to try it, but since BIOS upgrades can be dangerous (and even in cases where they they don't brick your board, it can be a mighty hassle to recover), please note that I cannot provide support should something go wrong - you break it, you keep the pieces.

In any case, here is what you do: download both the modded version 1.40 BIOS and the original version 1.30 BIOS, put both files on a USB stick (in my case, I had to put the VFAT filesystem directly on the stick without a partition table for the BIOS to recognize it), enter your BIOS and use the instant flash tool to first flash the newer 1.40 BIOS (which will downgrade the CPU microcode) followed by the older 1.30 BIOS (which will restore the OC menus).

After this, my BIOS settings were reset and I was able to enable "Multicore Enhancement" to achieve an all-core 3.8GHz "overclock" on my non-K i5-4670 CPU (core ratio must be set to auto for this to show up).