you could use the legacy with asic option and limit it to 2GB for 4GB cards.
Which means to add this:
and set in ReBarState.exe 2^11?
I actually tried only adding this Registry key and it didn’t make a difference. If I understood correctly, it is because this key is relevant for 8GB VRAM minimum (only for GCN architecture).
exactly!
just rebar state at 11 and you’re good to go
since the non asic only exposes the memory stuff (amernime said himself), while the true rebar for gcn is the one with asic
oh btw, could you tell us how did you mod it (like step by step)? i had time struggling to get a good way to mod an asus board.
I think I don’t get the struggle modding Asus. I just followed @Kuri0’s WiKi on github, easy to follow up. I can help you mod if you want, but use at your own risk.
As for the ReBAR. Tried just now, sadly didn’t make a difference.
GPU doesn’t support Resizable BAR, maybe you could try another VBIOS because I’ve seen it work on cards of same generation
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Hi @Blizz,
Your Mainboard BIOS is fine now. You just need to work on the GPU driver / VBIOS problem.
Hi, Thanks for replying!
I’ve seen R9 280X works too. Hence I thought VBIOS only needs to support UEFI in order for ReBAR to work.
Any idea what VBIOS should I try? What do I need to look for in VBIOS to add ReBAR?
An update upon that lead:
I exported the BIOS file with ATI winflash 2.6.7 (since GPU-Z didn’t export it well cause GOP Updater couldn’t work with that) and used GOP Updater v1.9.6.5.d to patch with the latest GOP. Then flashed the patched VBIOS back with ATI winflash 2.6.7, but no difference whatsoever.
Also I tried every combination of ReBAR again. Set 11 in ReBarState.exe with legacy ASIC, without, set it to 32 and again with legacy ASIC and without.
@Blizz GOP isn’t what controls Resizable BAR, some other part of it needs to be updated to support. Best option would be flashing VBIOS of a similar card though it’s kinda risky
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Hi,
Hope everyone is having a good day/afternoon/night.
I need help with ReBarUEFI bios, been trying to patch the bios using the guide without any success. I keep getting an extra pad file when using UEFIpatch, and I’ve followed the MMOTools steps as well, but I am still not able to produce the correct bios file.
I’d appreciate if anyone can help me? I applied the normal patch and haswell usb3 patch.
Here is the Bios File link from Asus, CAP extension.
Asus Motherboard Z87-A
RX 580 8GB
I appreciate any help and/or guidance.
Edit: did a little more digging into 4G decode/Above 4G, seems my MB might not support this. GPU-Z is showing yes, but I hear it can be wrong. I extracted the IFR txt from the bios, and searching the text, I wasn’t able to find anything related to 4G.
Update: I flashed the rebar-bios using hw flasher (CH341), and I am able to get 1GB resizable bar working, anything bigger I get a black screen. I don’t think my motherboard has the 4G decode support. Is there anything else I can try?
Thanks
@ Mak3rde patch does not seem to be recognised by the z170x Gaming 7 model.
i am running on Windows 11 but have also converted an old boot drive running Windows 10 from MBR to GPT and same issue there too.
i have tried reflashing the VBIOS of the A770.
i have enabled the onboard iGPU and reduced the minimum and maximum memory to the lowest settings.
i have a feeling it may be something to do with the Don’t downgrade 64 to 32 patch. perhaps this board requires a slightly different patch.
Hi @ComicalHeretic ,
It is almost certainly the problem. The pattern isn’t there, so the patch isn’t applied.
I’ve applied the patches to most of these boards and varoius revisions, the @ Mak3rde patch doesn’t apply to any of them.
A new patch for this is needed. It isn’t the first time someone wanted to get ReBAR working on these Gigabyte Z170x boards.
It’s a shame the 2GB BAR doesn’t work for the time being, as the intel driver was happy the last time I tried 2GB.
it says that it rolled back to factory F4. does it mention if they were using the latest firmware with the patch or an older firmware?
i have seen another post also similar where there is no display at post but comes good in windows. both seem to be using AMD GPU. perhaps my issue is due to being an Intel GPU. i am still trying to source another PC to test my card with my previous card was a 660ti which shows as unsupported in GPU-Z so was unable to test rebar with that. i have also found that if the iGPU is enabled it starts giving me random entry point dll failures on a number of applications upon bootup. once disabled the issues go away.
Hi !
I have a maximus hero 8 (non alpha) and I would like to know if it would be possible to share a mod bios with resisable bar to activate ? 4g decoding and cms are already editable in the bios
I use the latest version of the bios available on the asus site but I can change version if necessary
Thanks 
I tested your bios with ch341 and usb flashing but nothing work ! Just a bad bios. I tested to parch my bios myself but the reBar doesnt turn on 
Hi,
Yep, i juste forgot to use "Don’t downgrade 64-bit BARs to 32-bit (by @Mak3rde)” and finally its work fine 
thanks
I tried modding my Asus P9X79 Pro with Reziable BAR, but I now get Error code 19 and no output.
I tried holding MemOK! button for 3 seconds but no change, tried resetting CMOS and still no use.
Here is my BIOS (4.8 MB) if you want to take a look at what I did wrong (Sata drivers where modded long ago and it worked just fine, as well as network and NVME).
I have 64GB of RAM (I think I read on a post here that removing RAM modules worked, but I want to keep my 64GB of RAM), but I applied the patch, and since it’s HEDT I don’t need to DSDT patch it. Also didn’t notice any corruption in Pads (but I might missed something I wasn’t aware to look at, I don’t know).
Help would be much appreciated! Thanks!!
EDIT: I made a BIOS where the only difference is that I set Above 4G-Decoding to USER in AMIBCP and flashed it (in two places), apperantly it still doesn’t show up in BIOS so I can’t really enable it. Maybe related?