B550 Pro4 Low Resolution in BIOS/WinPE
Printed From: ASRock.com
Category: Technical Support
Forum Name: AMD Motherboards
Forum Description: Question about ASRock AMD motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=113412
Printed Date: 01 Feb 2026 at 5:38pm
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com
Topic: B550 Pro4 Low Resolution in BIOS/WinPE
Posted By: Quexos
Subject: B550 Pro4 Low Resolution in BIOS/WinPE
Date Posted: 16 Dec 2025 at 12:42am
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When booting up a WinPE based "rescue.iso" for imaging software like Macrium Reflect, Hasleo Backup Suite, etc. I get a very low (unusable in some cases, the app won't even fit in the screen) resolution of 800x600 I think it is. I think it is 1024x768 in the actual BIOS/UEFI, and I can tell GRUB to do 1080 and it will, but it defaults to something really low. When installing Windows itself, the resolution is at 800x600 and greyed out, until I get the GPU drivers installed, making it almost impossible to navigate the setup. 800x600 is below the minimum most apps are designed for these days and the "Next" or "OK" buttons and other required dialogs are totally off screen. I've had this problem on three different 1080p monitors, and four different GPUs, 2 Nvidia 10 and 16 series, and 2 AMD 6000 series RDNA2. One BIOS version, v2.10 from 2021 worked properly, but all since then have the problem. I can not go back to 2.10 because I have a Ryzen 7 5800XT CPU that requires v3.41 or newer. When I ran with CSM = enabled and used legacy BIOS and MBR disks, it worked better (don't remember if it was full 1080p or just higher than 800x600), but running UEFI and GPT disks with CSM = disabled as it must be to use Resizable BAR, I have issues. Any ideas? Setting that "Full HD" (or similar, from memory) option in the BIOS to Auto or Disabled makes no difference. I could run Legacy/CSM/MBR but I'd lose a lot of modern features and performance. |
Replies:
Posted By: Quexos
Date Posted: 16 Dec 2025 at 1:00am
| No edit function? Anyway, I know BIOS 2.10 worked from when I had a Ryzen 5 5600 CPU in this main board, but am afraid to try it with a 5800XT that didn't even exist when that BIOS was released. Also, if my memory serves me, my Asrock B450 Gaming K4 had the exact same problem, only I always ran it in Legacy BIOS mode so just didn't care. |
Posted By: Xaltar
Date Posted: 17 Dec 2025 at 5:42pm
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That is an interesting issue. It may be worth opening a support ticket and asking ASRock about it directly: https://tw.asrock.com/events/tsd.asp" rel="nofollow - https://tw.asrock.com/events/tsd.asp The line in your user manual that says "Please do not disable unless you?™re running a WHCK test." is interesting and may hold a clue as to what could be happening. Have you tried enabling resizable bar without disabling CSM? I haven't played about with it myself but I recall something about some users keeping it enabled while enabling resizable bar and above 4g decoding. Google's ever helpful AI seems to think it's impossible but may be worth a shot. One of the video tutorials I watched stated it was only necessary to disable for secure boot. I don't have a running 500 series AM5 system to test with right now. ------------- 
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Posted By: Quexos
Date Posted: 18 Dec 2025 at 5:31am
Yes. What happens is the "Above 4G" option becomes greyed out and unchangeable, but still reads Enabled. The Resizable BAR option still says Enabled, and can still be accessed/changed, but it does not actually work at all back in Windows or the AMD GPU driver. I have no idea why. If memory serves me the Above 4G setting has been in BIOS'es way back before UEFI and CSM existed. Isn't that the one folks would turn on to allow a 32 bit OS to access more RAM or something like that? |
Xaltar wrote:Posted By: Quexos
Date Posted: 18 Dec 2025 at 4:46pm
Done. they were about as usefull as I expected they would be: On 12/17/25 8:26 PM, Pablo wrote: "Motherboard does not support the type of windows PE version . Support regular windows 10 and windows 11 only" |
Posted By: Xaltar
Date Posted: 18 Dec 2025 at 5:41pm
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Ouch, sorry to hear that. I guess it makes sense with how harsh the market is these days. Even I have to watch what I say incase someone tries to use my words as "but ASRock said.." and I am just a community moderator. I have noticed the support teams of most board partners (all really) have really locked down what they provide assistance with these days. It's a pity, ASRock's support team was one of the best where it came to supporting "unsupported" OSes and such. At least you got a response. I haven't tinkered with Windows PE since XP days so I am afraid I don't have anything I can contribute. -------------
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Posted By: Quexos
Date Posted: 19 Dec 2025 at 6:51am
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Yeah, I have never gotten any actual support for any PC hardware, usually don't need any. I gave up trying decades ago. It just works or you RMA/return. In this case I told them the issue happened in the imaging software rescue disks, which run on Windows 10 PE straight from the Windows 10 install, and in Windows 10 and 11 itself before my graphics drivers get installed. The answer is it's the wrong type of PE and it only supports Windows 10 and 11. I JUST told him it was Windows 10 itself! It's like they don't even read the question. Anyway it worked well in BIOS 2.10 so it is clearly a BIOS issue in all BIOS' since and will never be fixed. I was open to the possibility I missed a setting somewhere or something though, but have tried pretty much everything, including different CPUs, GPUs, monitors, and every conceivable BIOS configuration. Guess I'll just have to live with it or do without UEFI/GPT/Resizable BAR. |
Posted By: Quexos
Date Posted: 22 Dec 2025 at 6:35pm
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Woah! Asrock responded a second time and sent me a "custom" BIOS to try out and it worked! I'll be danged! Props to them. Latest BIOS is 3.90 and they sent me 3.90a which behaves like v2.10 from 2021/8/5, the last one that worked properly for me. That 2.10 BIOS was from before I even bought the board. Mine shipped with v3.40 in 2024, so it was always borked until I tried the older BIOS, which is too old for my current CPU though. I have not used it (v3.90a) long enough to see if there are any other/new issues, but I expect not. |
Posted By: Xaltar
Date Posted: 22 Dec 2025 at 8:28pm
Now that is more like the ASRock I know and love  It most likely is based on the latest stable release with only the change needed for PE to work properly altered. -------------
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Posted By: Quexos
Date Posted: 23 Dec 2025 at 3:10am
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Considering so many other BIOSs have gone by that were "borked for me" but I've not heard anyone else complaining, I wonder if it's not a one off on my particular combination of hardware or something. It was the same on my Asrock B450 board that is now in my second PC though (running legacy MBR), so I just figured it was how UEFI/GPT behaves and always avoided it...but apparently not. I suspect they actually grabbed the old 2.10 BIOS and copy pasted some relevant part of the code/package into the current 3.90 BIOS for me. We'll see if they release a "new" BIOS eventually (the board is getting a bit old now) with the fix I guess. If this was a wide spread problem, I'd have thought they would have heard all about it from everyone else by now. Who knows though. Most folks probably don't spend nearly as much time in PE/imaging software/Windows installers, etc. as I do though. I tend to tinker a lot, and fix things until they break! Here's the still odd but better results I get with a 'rescue.iso' made from Macrium Reflect 8.1: 1. Boot from a usb flash drive in legacy BIOS mode = can change resolution to any, large list available. 2. Boot from a usb flash drive in UEFI mode = only get 2560x1080 native, no other options. This used to be unusable 800x600. 3. Boot from same files copied from ISO to partition on GPT SSD drive UEFI = 1024x768 no other options, but at least it's not 800x600 with no options! Three is odd. Same boot files and UEFI mode, different behavior just because of USB vs SSD drive source?!? |
Posted By: Xaltar
Date Posted: 23 Dec 2025 at 5:30am
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Oh, the tech person you spoke to most likely had the BIOS custom made for you, either themselves or asked one of ASRock's BIOS team to. This is exactly why I still use ASRock products. I have seen this here on the forums more times than I can count. They often go above and beyond to help users. Thanks for the extra info. If you are willing, could you share the BIOS they sent you here so other users that need it in the future can find it. It will likely remain relevant as we are likely not going to see any more AM4 CPUs released now. -------------
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Posted By: Quexos
Date Posted: 23 Dec 2025 at 11:26am
Sure. If someone stumbles here from a search, it may save them some trouble! I don't see any way to attach it but I'll share it on my G-Drive for now. If there's a better way/place to share it, let me know, or just grab it and put it there or whatever. I included an Info.txt in the RAR archive file to tell where/why it came from and what board it's for. https://drive.google.com/file/d/1XtHUY0dK2Q-d6qrx6ZRSOG7uKW7hPH4N/view" rel="nofollow - Asrock tech support Low Resolution Fix BIOS v3.90a 21 December 2025. https://drive.google.com/file/d/1XtHUY0dK2Q-d6qrx6ZRSOG7uKW7hPH4N/view |
Posted By: Xaltar
Date Posted: 24 Dec 2025 at 3:32pm
Thanks Quexos, hopefully it will help someone else down the line  -------------
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Posted By: Quexos
Date Posted: 25 Dec 2025 at 6:11am
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More info/FYI: It still behaves oddly. Long story short, I get weird mixed results, but no 800x600 bad ones! For example, booting into Macrium Reflect PE "rescue disk" from an ISO on a "Ventoy" USB thumb drive in UEFI mode results in locked 2560x1080 (monitor native). Same in BIOS/CSM mode results in 2560x1080, but with a list of resolutions I can change to. This is the intended behavior. Booting from the same files with contents of the ISO copied/extracted to a GPT partition on my internal SSD results in locked 1024x768...if I hit F11 (boot override) and select that partition from the list. If I set that exact same partition to be the first/default boot device and boot to it that way, I get locked 2560x1080. Weird but good'nuff. |
Posted By: Xaltar
Date Posted: 25 Dec 2025 at 6:25am
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Thanks for the extra info and Merry X-mas! -------------
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