Intel was really not happy ASUS figured out how to enable multiplier overclocking on non-Z boards for even non-K CPUs and how everyone else quickly copied them. So their 2015 era microcode was updated to prevent this from working, and of course one of the biggest updates for BIOSes is updated microcode as CPU errata are discovered and fixed, so you either get fixes
or overclocks (plus note you can only boot from a NVMe disk with later BIOSes too). Worse, Intel told Microsoft this was a DEFCON 1 security emergency so ever since, WindowsUpdates will also
push later microcode to Windows if it detects your BIOS is too old, and that will also disable overclocking.
If you want to revert to an older BIOS than is allowed using Gigabyte flash tools, then you will need to remove the soldered primary BIOS chip and use a chip programmer, or just buy a new BIOS chip from eBay and ask the seller to put the F3, F4 or F5 BIOS onto it. But it is up to you to either modify your Windows, or use an older unsupported Windows to overclock.
Or you could overclock the Intel-approved way by getting a Z97 motherboard to go with your K processor. Honestly though, you already have a BIOS that supports 5th gen Broadwell-H CPUs and one of those would be a much larger performance upgrade thanks to the extra 128MB L4 cache, even if you can't overclock it.
![](/proxy.php?image=https%3A%2F%2Fimages.anandtech.com%2Fgraphs%2Fgraph16195%2F118905.png&hash=c4016f0a13fe26d84f98a52bb001a981)
They are pretty competitive with up to 11th gen Intel on DDR4-3200, even with only DDR3-1600 since the extra cache makes up for that in games. This was when Intel was struggling to shrink below 14nm, with 5th gen being the first, and 11th gen the last one on 14nm eight years later. Your 11-year old 4th gen is 22nm.