Hi everyone, I hope to get help from a modder on this topic. I’ve been trying to modify the BIOS of my Asus X99E WS 3.1 USB to make REBAR work. I’ve tried a few different methods, but I still haven’t been able to flash it to my board. It’s not from a flash drive, because I used the original Asus .cap file and was able to read it. I noticed that every time I modify it, I lose the signature (AMI APTIO CAPSULE). I tried using a Hex Editor, but it still didn’t work. I know this might be easy for some, but I’ve been losing my mind for two weeks now. By the way, my setup is a Xeon E5-1660 v3 4.5GHz, 4x8GB, 2666MHz CL13, and an RX 6800XT. Best regards!
flash it with usb bios flashback
I have tried, but simply when loading a modified bios, the led blinks about 5 times and then remains solid, I have already confirmed that I have the correct name, I tried several pen drives and with the original bios the usb flashback can read it.
here, use FPT from Me System Tools v9.1 “fptw -bios -f bios.rgn“.
I downloaded ME System Tools v9.1 r7 but every time I open it and click on a key fptw64.exe gives me an error
use command prompt as administrator
Hi!
Could someone please help mod the BIOS for the ASRock X99 Extreme3 motherboard to enable Resizable BAR support? I’ve tried patching it myself using ReBarUEFI but ran into issues.
If anyone has a working modded BIOS file or could create one and share it, I’d be very grateful. I understand the risks and I’m comfortable flashing it.
Thanks in advance! <3
Hi could somebody help me i have a b365m ds3ch and ive tried doing the steps but dont really know what im doing and its i7 9700f with intel arc b580 i have rebar enabled in bios but shows it not working in setting on gp
uz and arc settings.
Total n00b here, so please be kind 
I bought an used PC with a Machinist MR9D Plus motherboard; my guess is that its BIOS was already modded, because:
- an Asus Hyper M.2 Card with 4x Intel P670 1TB NVME drives was included, and it works! (so it has bifurcation)
- I very briefly tested it with just CPU-Z, and multithreaded all cores are around 3200MHz (so I assume it is turbo unlocked)
- the GPU does not support Resizable Bar (but there is “Above 4G” in the BIOS); I tried to run ReBarState.exe but it gives me several errors
Now, if someone may be interested, the BIOS dump is here:
If some guru may give a look and find a way to add ReBar, it will be wonderful!
@villegta Try This: X99 Extreme3_Rebar.zip (6.7 MB)
@zozzone Try this: X99-MR9D_Rebar.zip (3.1 MB)
For Normal Rebar, Run this rebar state as admin to enable
For Nvidia Turing Only (GTX 16xx/RTX 20xx/Quadro RTX/T series), Run this rebar state as admin to enable.
If your motherboard doesn’t have Bios Flashback, then you would need to use an external programmer for it.
Have you check in the bios that csm mode is disabled, everything is UEFI? If so, then probably you could ask gigabyte support for a new bios by explaining your problem.
“…ask gigabyte support…” for a Machinist motherboard?!?
By the way, I made my homeworks and found several BIOSes with ReBar, but I’m afraid to brick my motherboard…
Hello please help me to add re-size bar support to my asrock z170 gaming k4
Fatal1ty Z170 Gaming K4, don’t enable Above 4G Decoding on this motherboard it may cause the device to brick.
As for now, resizable bar toggle isn’t viable to be implemented through the bios gui because the implementation is different than official one. Above 4G Decoding could be unhidden tho, since the toggle is there in the bios.
Just take a note that if you do 32gb (4x8GB), bar size above 8GB might not be possible due to limited address space, the same does happen to z97/h97 (and maybe a 8 series chipset that does support above 4g decoding) but this is due to some unconfigured thing in the bios iirc that limits the address space to 36bit max, same as ivy bridge. But if you use X79 or X99, with above 4g decoding is available in the bios wether it’s hidden or not, you could use more than 8GB Bar size.
[REQUEST] ASUS Maximus V Formula (Z77) ReBAR Mod - Technical Suggestion for Implementation
Dear BIOS Modding Experts,
Following up on my request for a ReBAR mod for the ASUS Maximus V Formula (Z77), I understand that implementing the full ReBAR GUI toggle is complex.
I would like to propose a potentially easier and highly optimized implementation for any modder willing to take on this challenge:
Technical Proposal for the 1903 BIOS Mod:
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Automatic Activation: Instead of showing the settings, could the mod be implemented to automatically force-enable both Above 4G Decoding and Resizable BAR (rBAR) when CSM is set to Disabled (Pure UEFI Mode)?
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Addressing Optimization (32GB RAM): My system utilizes 32GB (4x8GB) DDR3 RAM. To maximize the addressable space for Above 4G Decoding and ReBAR on this Z77 platform:
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Could the modder consider removing unused legacy modules (such as the CSM/Legacy Boot-related modules) from the BIOS?
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This should help free up crucial memory space, allowing the Arc GPU and the full 32GB RAM to be utilized to their maximum potential via ReBAR.
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This approach should simplify the modding process while delivering the best possible performance for Intel Arc on the Z77 platform.
Thank you very much for considering this technical request!
Best regards
Following up on my request for a ReBAR mod for the ASUS Maximus V Formula (Z77). I have now analyzed the 1903 BIOS with AMIBCP and confirm the following:
- Two “Above 4G Decoding” entries exist (one in Extreme Tweaker and one in Advanced → PCI Subsystem Settings).
My Updated Request:
Could you please modify the BIOS to ensure that the necessary code for Resizable BAR (rBAR) is injected and that BOTH “Above 4G Decoding” settings are force-enabled in the background when CSM is Disabled?
I believe this, combined with removing unused legacy modules (to maximize address space for my 32GB RAM), will be the key to enabling full Arc performance.
I am looking for an expert to implement this code. Thank you!
Download M5F.cap ( Modded with the 4 G Decoding ) ASUS MAXIMUS V FORMULA BIOS 1903 modded for NVMe boot drive and EFI updates
I dont know how can mod the Bios, can only read it an try to understand what going on, but i dont know how to modding this file…
HERE: The Program to open and read or modify this Bios File ( AMIBCP )
Hello @Albert-Meilenstein
Is the Memory Remap Above 4G not visible in the advanced menu somewhere ?
Also, are you able to use the BIOS Flashback feature properly?
Before trying anything, make sure you can recover from a bad flash or bad mod.
The instructions for Flashback are in the user manual.
Hello @68k-dude,
Thank you very much for your help and caution!
I have an important clarification and a safety update for you regarding the mod:
Goal: Full UEFI for ReBAR
We are strongly in favor of converting the BIOS to a pure FULL UEFI BIOS. This means the CSM mode (Compatibility Support Module) should be irrevocably set to “Disabled” and ideally, the entire legacy CSM code should be removed.
The goal is to gain more space in the BIOS memory by removing the old CSM code. This space is intended to be fully utilized for the necessary ReBAR addressing and full memory mapping, which is key to optimizing performance.
Above 4G Decoding and ReBAR Implementation
Regarding the ReBAR requirements:
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Memory Remap Above 4G / Above 4G Decoding: I have checked all menus (including Advanced and Extreme Tweaker) and the option is not visible. However, I confirmed using AMIBCP that both “Above 4G Decoding” entries are indeed present in the 1903 BIOS code (one in Extreme Tweaker, one in Advanced/PCI Subsystem Settings). This is why I am requesting the mod.
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My ultimate goal is for you to implement the ReBAR code and force-enable the two existing Above 4G Decoding switches, as detailed in my updated request.
Safety & Recovery Assurance
You can proceed with full confidence regarding the risk:
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BIOS Flashback / Recovery: Yes, I can confirm that I have full recovery capabilities. I have previously performed BIOS chip replacements on this specific board to recover from errors, so I am confident in handling the risk of a bad mod.
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Extra Chips: I have also proactively ordered and received 5 replacement BIOS chips. If anything goes wrong during the modding process and the built-in BIOS gets bricked, we have immediate replacements available.
Thank you again for your valuable time and expertise!
Best regards
Just to clarify, I am not able to perform the BIOS mod myself. I have only used AMIBCP to read the current BIOS structure and confirm the existence of the entries. I wouldn’t know where or how to program or change anything in the code.
A quick note to EVERYONE here: If you need BIOS chips, you can purchase them here: Bios-Chips, ASUS MAXIMUS V FORMULA, kaufen ab 9,95€, neu, inkl. Programmierung | www.biosflash.com
Hello First off im very sorry when this is not the correct topic/category ive just learned some people managed to use resisable bar with rx570, Now i asked GPT my best friend because i dont know ssh*t i dont even know if it will help, but from what ive heard/learned i have to mod or activate 4g decoding but gpt said my motherboard probably doesnt have this function, and said to me maybe the people in Win-raid can help.. im an avg pc user, but ive never modded something.. Can someone help or clarify if its even worth it? i dont know if u need the other specs like i have the i5-4430, rx570 (8gb) the h81M-plus board and 16gigs of RAM.. im very sorry if this post is rude/wrong false category or not the right/correct topic? Also my big apologies for my bad english, but i cant ask gpt for translate thats just not me? excuse me! 
its probalby not worth it at alll to do this?