Need help from specialists.
In my new 2025 BIOS for the Gigabyte Z370PD3 board, which I received from the support service, it is impossible to disable above 4G decoding in any way. If you enable CSM, then it is impossible to get into the BIOS. I need CSM.
I also tried to disable above 4G decoding using AMIBCP_5.02.0034 first, then flash the BIOS, it did not help.
Resetting the BIOS via clear CMOS does not work.
All other BIOS settings work and are saved.
Everything worked on the old 2021 BIOS.
It seems that something prevents me from disabling this function.
Maybe someone knows a solution to the problem?
Thank you.
The issue is your dGPU that doesn’t have Legacy fw image vBios, only has modern EFI firmware vBios for UEFI environment.
Confirm your dGPU firmware and request it to GigaByte.
EDIT:
Oh… and you forgot to mention this… just great!!!
Anyway, if it’s the same for iGPU use UEFI Editor and share here the “newly” Gigabyte bios.
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I also used coffeeTime_099 to update Vbios, GOP, OROM. On the old BIOS everything worked without problems. On the new one only 4G Decode does not turn off.
with the video card and with integrated graphics the same.
What kind of bios did you ask gigabyte support? If you don’t mind, you could share the stock (not dumped bios, the one GB support gave to you) here.
What are you trying to achieve (since you used coffeetime)? Also, what are your current specs?
I am trying to enable CSM support.
Here is the BIOS from support.
Z370PD3.F16c.zip (6.3 MB)
First I used the original BIOS, then the modified one, it didn’t help.
So with old 2021 bios you mentioned, both full uefi and csm works, but the bios you requested to gigabyte support have above 4g decoding enabled by default, csm disabled by default, and when you disable both above 4g and csm, it just wont boot up?
Sorry, but im kinda confused here, since if old 2021 bios works normally in both modes, why did you ask for a new update (as per my question on first reply)?
Everything works with old BIOSes. In the new BIOS, CSM was enabled by default, I had to disable it in AMIBCP beforehand, otherwise I couldn’t enter the PC BIOS.
New BIOS includes security updates for Gigabyte motherboards.
So you mean csm was enabled by defualt but also above 4g decoding is also enabled by default, where it should be disabled by default, and the toggle/settings of above 4g decoding is not shown in the bios?
4G seems to be turned off by default, but when I turn on the PC, 4G turns on for some reason, I turn it off and save, restart and it turns on again.
I don’t want to think about the sad, but could it be that the new BIOS is broken?
Is there any solution?
you did say that amibcp did work with your new F16c bios, did you only set the above 4g disable on optimal only, not on failsafe?
If you did disable the above 4g decoding in the bios, enabled the csm, and it works untill you shut down your pc (lets say you cut the power to the pc), your cmos battery might be dead, otherwise the bios must’ve been bugged.
I had the similiar issue on stock h77 ds3h bios, it randomly reverts to default/failsafe settings on a very random interval (could be a week, or 2 weeks, on me it shows bios has failed, reverted to default screen and the option to load bios settings etc.), turned out the cmos battery has dropped below 2.2v, replaced it, and never had that issue again.
You misunderstood. I had the original BIOS from support, but when I started it didn’t allow me to go into the BIOS settings, so I had to disable CSM in AMIBCP first and also disabled 4G, but that didn’t help.
The battery is new, 3.2V, but it still doesn’t work.
Also more info. when starting the PC with the new BIOS, I can hear the fans speed up for 0.5 seconds, then I press DEL and see 4G is turned on again.
I repeat, on the original new BIOS it is impossible to get into the settings, because 4G is turned on.
This was not observed on any of the old BIOSes.
Ok, this booting with iGPU or dGPU on F61c? What’s your CPU model and dGPU model?
By default (F16c no MODs/no CTime) is the option A4G available and allows changing Enable/Disable?
We have to assume a wrong/incorrect/downgraded/upgraded iGPU mb vbios/OProm (from CTime)… you need to debug this to make any sense to trace it… else no one can help you with such mess.
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Of course, I used a motherboard with a minimum of peripherals, an i3-9100 processor. 8 GB of Micron RAM.
First I flashed the original BIOS z370pd3.f16c and got a black screen.
In AMIBCP I previously disabled CSM, otherwise nothing.
This is the first thing I thought of doing, then I flashed and only then was I able to get into the UEFI BIOS settings.
I use a radeon R7 250 with GOP UEFI, this does not solve the problem.
Yes, this is only on the Z370PD3.f16c BIOS.
Yes, all options work and are saved, except 4G.
The 4G option is active, I set it to off, save, reboot, enter BIOS, re-enable.
re-bar can also be enabled or disabled.
Sorry for the bad English.
The system does not allow me to send more than 20 messages per day.
Thanks/
P.S . I always use Gigabyte motherboards, they have never broken, they are a very good company.
support service. But that doesn’t solve the problem.
Well…this is a very confusing situation, Gigabyte non-public bios F16c naybe bugged, and you need to report this issue you’re experiencing.
The mb by default supports Coffee Lake and ReBar on latest F15b and F15…don’t see the need to mess with ReBar mod and CTime…
I would advise further test by flashing the “pure” F16c again, shutting down the system, AC off, remove CMOS battery, leave it to drain for 5m with CMOS battery holder shorted on pads.
Power up the system with a different memory module or half of it, not the same 8Gb if it’s only on 1 stick. Try iGPU boot and dGPU boot, no OS boot (disconnect any disks) use another dGPU card model if possible.
The system must boot in any of the 3 settings by bios default (UEFI, CSM ON or AUTO) as both CPU and iGPU supports it, as it has the following versions on it:
EFI GOP Driver SKL-AML - 9.0.1080
RAW GOP VBT SKYLAKE - 212
OROM VBIOS SKL-AML - 1060
Report the symptoms observed, black screen, no signal, blinking cursor on corner, beep codes etc…
EDIT:
F16c has the latest ones available and includes the latest CSME v11…up to date.
Good luck.
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Indeed, this is a problematic situation.
I also tried to change the BIOS microcode with the binary editor Hex Editor Neo, it didn’t help.
Thank you.
This is not possible to resolve at this time. Thank you
F16c has the latest ones available and includes the latest CSME v11…up to date.
I used this.
Everything works on the z370pd3.f15 BIOS.
No problemo/
What lead you to inquire Gigabyte for a “new” bios and what did they reported to you about the release?
Hello.
For H110 motherboards, there is this 2025 BIOS update, but for Z170/Z270/Z370 there is none, so I asked support.
This BIOS update addresses critical security vulnerabilities (CVE-2025-7026, CVE-2025-7027, CVE-2025-7029) identified by BRLY.
GIGABYTE strongly recommends all users update their system BIOS immediately to protect against potential security risks.
It is possible that for Z370 this is not critical, since it is not there, so I continue to use the latest BIOS from the F15/ site
There is also information here.
https://www.gigabyte.com/Support/Security/2302
Thank you!
I think it is better to ask gigabyte esupport again (just reply to the latest mail where they give you the bios) for another bios, explain the “bug” you have been experiencing.
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