Is it possible to run a i5 9400 on a Z170 Pro4S?

Hello! I’m new to the forum!
I’m currently running a i5 6400 on a z170 Pro4s (SMBIOS 2.8). I’ve found a second hand i5 9400 for dirty cheap. I’ve read that with some modification to the bios is it possible to run it with my current motherboard. Is it true? Can you link me all the documentation? I’m a totally newbie!

[TOOL] Easy automated Mod tool for Coffee Lake bios - BIOS/UEFI Modding / BIOS Modding Guides and Problems - Win-Raid Forum (

[GUIDE] Coffee Lake CPUs on Skylake and Kaby Lake motherboards - BIOS/UEFI Modding / BIOS Modding Guides and Problems - Win-Raid Forum (

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So there’s no difference between a 9400 and 9400k?

There’s no i5 9400K, only 3 desktop sku’s 9400, 9400T and 9400F… are you in a special country that have 9th Gen i5 9400K ???

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Sorry, it’s late and I’m very tired :frowning: In the image of the first guide you’ve linked I’ve misread the 9600K as 9400k. In the picture I can’t see any 9400, so how do I know what pin do I have to isolate/connect? The stepping is going to be similar?

Sir… You’re tired and i not losing my time searching the info for you, so if it’s no time for a good reading on those threads… try another day and you may find the info you need, any questions issues, post on the relevant threads linked previously, not here, i just pointed you the right direction, good luck.

@BossettiFreedom Have a look on the top of the i5 9400’s IHS (Integrated Heat Spreader) for the S-Spec.

All 9400’s are either a true 6 core die or a cut-down 8 core die and the S-Spec can tell you this.

The S-Spec will determine which CPU microcode you will need to insert into the BIOS e.g.

i5 9400 with S-Spec SR3X5 (Revision U0) = CPUID 906EA (true 6 core die)
i5 9400 with S-Spec SRELV (Revision P0) = CPUID 906EC (cut-down 8 core die)
i5 9400 with S-Spec SRG0Y (Revision R0) = CPUID 906ED (cut-down 8 core die)

All of these CPU revisions will require CPU socket isolation.

Only B0 revision (4 core die) can work without CPU socket isolation.

This map shows which pins to isolate for ASRock.

Note that you will also need to connect 2 pins for the motherboard to detect the CPU is present.

You can use CoffeeTime v0.99 to modify your BIOS but you will likely need a hardware programmer to flash the modified BIOS.

Don’t forget to downgrade ME Firmware to version 11.7.1xxx or the CPU won’t boot

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