Help with stretched res on 23.8 inches of display, using a 27 inch monitor

[99muppets]

Hi, I am aware this is probably a really specific and weird request, and I have found absolutely nothing online to try and help me with this. I'll give the rundown.

Currently, I have a 23.8 inch display, and a 27 inch display. I play lots of competitive fps games, and have played on strictly ~24 inch screens forever, 27 inch I find is FAR too big (Yes i've tried pushing it back, its simply not the same). I am planning on upgrading to a 27 inch 480hz OLED (the one by LG), and simply running it on a lower resolution with the "center" scaling mode in amd, to play on a 23.8 inch screen essentially.

However, I am trying to do some initial testing first with my current 27 inch panel, and it's super easy to just setup a 23.8 inch resolution and click centering in my amd panel, but because I have to select no scaling, I can't play stretched resolution in any games (which I have used for basically every fps game i've played in the last 5 years, so I would really love to use it). I've tried CRU, and i've found some very strange behaviour, I would really love some help with this.

What I want to accomplish exactly:
2560x1440p @ 27 inches, using a resolution of 2272x1278 @ ~23.8 inches of active display size, while still retaining the ability to use fullscreen scaling mode in amd, in order to have games stretch / scale to fit the 23.8 inch screen, instead of stretching to fit the 27 inch screen.

Some more quick pre-amble before I show what i've attempted; 2272x1278 is EXACTLY 16:9, and approximately 23.8 inches, however i've read that its best for the resolution to be divisible by 8? Not sure if thats relevant, and if so, in that case is the resolution 2288x1288 better for what I want? its not EXACTLY 16:9, but both the height and width are divisible by 8 and its very close to 16:9.

Using CRU, I deleted every resolution in every single detailed resolution and resolution tab. Added a resolution of 2272x1278, restarted and wanted to see what would happen. Extremely weirdly, no matter what scaling mode I set on the AMD control panel, it would fill the whole screen (all 27 inches), but when I selected another resolution in the windows display section, it would only display the exact pixels of the other selected resolution. Say i selected 1920x1080, it would NOT stretch to the full 27 inches, it would have black bars above and below, AGAIN regardless of what scaling mode I set, so that behaviour makes absolutely no fkn sense to me. Essentially, I am trying to simulate that the DEFAULT monitor resolution is 2272x1278, so using full screen scaling will attempt to fit any lower resolutions I set in games to that resolution @ 23.8 inch of displaying pixels.




Above are a screenshot of the CRU setup i did and a screenshot of my windows display settings showing the active signal resilution was indeed 2272x1278 even when picking another random resolution, however noting again, it did not scale to the 2272x1278 size no matter what scaling mode I set, and when just using the 2272x1278, it would fit my whole panels screen no matter what scaling mode I set.

Is what i'm trying to accomplish even possible? Could I get some help with CRU, or anything would be really helpful. Cheers , my discord is 99muppets if anyone who is willing to help me would find it easier to communicate directly there.

[ToastyX]

The scaling mode in AMD's control panel is for GPU-scaled resolutions only. For resolutions sent to the monitor, you need to change the scaling mode in the monitor's OSD, if it has the option. The active signal mode is the resolution sent to the monitor. The first detailed resolution is considered the native resolution. The native resolution is always sent to the monitor even if GPU scaling is enabled because GPU scaling scales lower resolutions to the native resolution.

What you want to do is possible if the monitor accepts 2272x1278 and has a center scaling option. Then you can make 2272x1278 the first detailed resolution like you did here with the scaling mode in the monitor set to center, and then enable GPU scaling in AMD's control panel with the scaling mode set to full. Then lower resolutions will be stretched to 2272x1278 by the GPU, and the monitor will center the stretched resolution. You don't have to worry about multiples of 8 if the monitor displays the resolution correctly.

A better option: some monitors have an option to scale the picture down to a smaller size. I checked the manual for the LG 27GX790A, and it has a 16:9 24" scaling option that seems to do what you want. In that case, any resolution sent to the monitor will be stretched to 16:9 and centered to 24", so you can just use the resolution you want to stretch directly instead of scaling to 2272x1278.

For monitors without that option, there are several issues you need to consider:

1. The monitor must be able to handle lower resolutions. This is usually the case, but monitors with NVIDIA's G-SYNC processor usually don't support non-native resolutions. FreeSync or "G-SYNC compatible" monitors are usually fine, but some monitors won't handle the full refresh rate at lower resolutions. Unfortunately the specs won't tell you whether it can handle lower resolutions correctly.

2. The monitor must have a center scaling option. Most monitors that accept lower resolutions will have this option, but some don't. You can download the manual and check if the monitor has scaling options.

3. You won't be able to define 2272x1278 @ 480 Hz as the first detailed resolution because of the pixel clock exceeding EDID limitations, but you can define 2272x1278 @ 60 Hz to make the native resolution 2272x1278, and then add 2272x1278 @ 480 Hz separately in a DisplayID extension block.

4. If you also want to use 2560x1440, you need to check if adding it doesn't affect the scaling. GPU scaling should still scale lower resolutions to 2272x1278 if it's the first detailed resolution even if 2560x1440 exists separately, but Windows also does this annoying thing where it favors the current resolution to avoid mode switches when changing the desktop resolution, so it might end up scaling lower resolutions to 2560x1440 instead of 2272x1278 if you're using 2560x1440 and don't change to 2272x1278 first.

5. I know you're using AMD here, but NVIDIA's driver disables custom resolutions and ignores EDID overrides if the pixel rate for the highest resolution and refresh rate is high enough to require splitting the resolution between two heads internally, which is the case for 2560x1440 @ 480 Hz, so CRU would have no effect. I'm not sure how AMD handles this situation, but I haven't heard any complaints from AMD users. Keep this in mind if you ever plan to upgrade to an NVIDIA GPU. Hopefully they'll work this out in future drivers or GPUs.

6. A few games such as Fortnite insist on using the native resolution, so making it stretch would require forcing it to use a lower resolution somehow. Normally people do this by making the lower resolution they want the native resolution and changing the scaling mode in the monitor to full, but that won't work in your case because you need it to be centered, so you would need to find some way to force the game to use the resolution you want.

[99muppets]

(11-30-2024 04:53 PM)ToastyX Wrote:  The scaling mode in AMD's control panel is for GPU-scaled resolutions only. For resolutions sent to the monitor, you need to change the scaling mode in the monitor's OSD, if it has the option. The active signal mode is the resolution sent to the monitor. The first detailed resolution is considered the native resolution. The native resolution is always sent to the monitor even if GPU scaling is enabled because GPU scaling scales lower resolutions to the native resolution.

What you want to do is possible if the monitor accepts 2272x1278 and has a center scaling option. Then you can make 2272x1278 the first detailed resolution like you did here with the scaling mode in the monitor set to center, and then enable GPU scaling in AMD's control panel with the scaling mode set to full. Then lower resolutions will be stretched to 2272x1278 by the GPU, and the monitor will center the stretched resolution. You don't have to worry about multiples of 8 if the monitor displays the resolution correctly.

A better option: some monitors have an option to scale the picture down to a smaller size. I checked the manual for the LG 27GX790A, and it has a 16:9 24" scaling option that seems to do what you want. In that case, any resolution sent to the monitor will be stretched to 16:9 and centered to 24", so you can just use the resolution you want to stretch directly instead of scaling to 2272x1278.

For monitors without that option, there are several issues you need to consider:

1. The monitor must be able to handle lower resolutions. This is usually the case, but monitors with NVIDIA's G-SYNC processor usually don't support non-native resolutions. FreeSync or "G-SYNC compatible" monitors are usually fine, but some monitors won't handle the full refresh rate at lower resolutions. Unfortunately the specs won't tell you whether it can handle lower resolutions correctly.

2. The monitor must have a center scaling option. Most monitors that accept lower resolutions will have this option, but some don't. You can download the manual and check if the monitor has scaling options.

3. You won't be able to define 2272x1278 @ 480 Hz as the first detailed resolution because of the pixel clock exceeding EDID limitations, but you can define 2272x1278 @ 60 Hz to make the native resolution 2272x1278, and then add 2272x1278 @ 480 Hz separately in a DisplayID extension block.

4. If you also want to use 2560x1440, you need to check if adding it doesn't affect the scaling. GPU scaling should still scale lower resolutions to 2272x1278 if it's the first detailed resolution even if 2560x1440 exists separately, but Windows also does this annoying thing where it favors the current resolution to avoid mode switches when changing the desktop resolution, so it might end up scaling lower resolutions to 2560x1440 instead of 2272x1278 if you're using 2560x1440 and don't change to 2272x1278 first.

5. I know you're using AMD here, but NVIDIA's driver disables custom resolutions and ignores EDID overrides if the pixel rate for the highest resolution and refresh rate is high enough to require splitting the resolution between two heads internally, which is the case for 2560x1440 @ 480 Hz, so CRU would have no effect. I'm not sure how AMD handles this situation, but I haven't heard any complaints from AMD users. Keep this in mind if you ever plan to upgrade to an NVIDIA GPU. Hopefully they'll work this out in future drivers or GPUs.

6. A few games such as Fortnite insist on using the native resolution, so making it stretch would require forcing it to use a lower resolution somehow. Normally people do this by making the lower resolution they want the native resolution and changing the scaling mode in the monitor to full, but that won't work in your case because you need it to be centered, so you would need to find some way to force the game to use the resolution you want.

Hi there , really appreciate the time taken for the response. I had a browse through the OSD and then the manual pages for the current monitor im trying to test shit on (the samsung g52a 27 inch), no mention of scaling anywhere. However, in the OSD section, i've found a setting that sets the monitor to 21.5 inches 16:9 (its actually around 23.5 inches which is very strange, but irrelevant).

When I set it to this mode, it does give me the black boxes around the sides and top, however the desktop / display resolution still shows as 2560x1440p which is a bit confusing to me, is the display then downscaling this resolution to fit the screen? If so, I have no idea what resolution i'd want to use for stretched res, bit unsure how downscaling works, or whats happening, wondering if you'd have any insight or explanation to what I could try? cheers.

Additionally, is there a calculator online to figure out what resolutions would not require two heads @ 480hz, as that does seem like it'll just fuck me regardless. I've already done some calculation with an online calculator that I found, since the lg monitor uses UHBR13.5 (why they used dp 2.1 and didn't go for UHBR20 makes no sense to me), a resolution like 1272x1278 @ 480hz, as long as im using 8 bit SDR, will not require DSC to be activated, now I'm not sure I can manually disable DSC in the firmware, but thats something at least.

I had a read through the manual of the 480hz LG, does look like "original" scaling mode may be what i'm looking for? Either way the 24 inch is close enough to 23.8 that I will almost certainly get used to it. But again, would that mode just keep the active resolution the same? and downscale the picture? I really do not know what resolutions I would then want to actually use in these modes, again appreciate your help )

[ToastyX]

You're thinking too hard. The active signal mode is the resolution sent to the monitor. The monitor can't change the active signal mode. That happens on the PC's end. The scaling options in the monitor will scale any resolution it receives using its own scaler. If the monitor has an option to scale the picture to 16:9 at a certain size, then all you need to do is send a 4:3 resolution and it will be stretched to 16:9 and scaled to the appropriate size and centered, so yes it would be scaling down if you send it 2560x1440. This would also work if the 4:3 resolution is stretched to 16:9 by the GPU first, but then it'd be scaling twice, which could reduce the quality. For monitors without a sizing option, you'd have to do the centering method I talked about, so it's better to go with a monitor that has a sizing option to avoid the potential issues. The centering option is called "Just Scan" on the LG monitor. "Original" is aspect ratio scaling. The 16:9 24" option is exactly what you said you wanted though.

The single-head limit for current NVIDIA GPUs seems to be around 1350 MHz pixel clock. You could squeeze in 1920x1080 @ 480 Hz, but the problem is the driver won't let you do any EDID overrides if the monitor exceeds the limit even if the EDID override doesn't, so you'd need a monitor that can disable DSC or doesn't exceed the limit.

[99muppets]

(12-01-2024 03:08 PM)ToastyX Wrote:  You're thinking too hard. The active signal mode is the resolution sent to the monitor. The monitor can't change the active signal mode. That happens on the PC's end. The scaling options in the monitor will scale any resolution it receives using its own scaler. If the monitor has an option to scale the picture to 16:9 at a certain size, then all you need to do is send a 4:3 resolution and it will be stretched to 16:9 and scaled to the appropriate size and centered, so yes it would be scaling down if you send it 2560x1440. This would also work if the 4:3 resolution is stretched to 16:9 by the GPU first, but then it'd be scaling twice, which could reduce the quality. For monitors without a sizing option, you'd have to do the centering method I talked about, so it's better to go with a monitor that has a sizing option to avoid the potential issues. The centering option is called "Just Scan" on the LG monitor. "Original" is aspect ratio scaling. The 16:9 24" option is exactly what you said you wanted though.

The single-head limit for current NVIDIA GPUs seems to be around 1350 MHz pixel clock. You could squeeze in 1920x1080 @ 480 Hz, but the problem is the driver won't let you do any EDID overrides if the monitor exceeds the limit even if the EDID override doesn't, so you'd need a monitor that can disable DSC or doesn't exceed the limit.

Cheers , i've sent a support request to LG asking if there will be a DSC toggle at all, or any options regarding it.

I think I misconstrued my previous question about the downscaling. Lets say the 24 inch mode physically displays AxB pixels, would it be important for me to know exactly the resolution that is displayed physically to avoid vertical scaling? (Again, I fully admit I don't understand the nitty gritty to how this stuff works and what affects screen quality and what doesn't, been trying to do some reading and asking on the monitor discord but people are just calling me ret*rded for wanting to use stretched res lol).

For example, lets say for the sake of it, the screen set to 24 inch mode would display say 1600x900 pixels. I would ideally want to be using a 4:3 resolution that has the height @ 900 pixels right? Or does it really not matter at all.

And in the testing with my current monitor, is there a way for me to figure out what resolution the montior is physically displaying? I've set it to 21.5 inch mode, but I'm unsure how to figure out what resolution exactly that checks out to be, I could manually try and calculate it, but that seems like it would be impossible to get perfectly accurate. Thanks again

[ToastyX]

Avoiding vertical scaling could increase sharpness depending on how the monitor scales. Unfortunately if the manual doesn't specify, there is no way to determine what resolution the monitor is scaling to without trial and error. It's likely something simple such as 1920x1080 to simulate a 1080p monitor because that would be the most obvious choice. You can verify by changing the active resolution to 1920x1080 and displaying a checkerboard pixel pattern in an image viewer that can display an image 1:1 without scaling: https://www.monitortests.com/pattern/pat...0x1080.png

[99muppets]

(12-01-2024 04:24 PM)ToastyX Wrote:  Avoiding vertical scaling could increase sharpness depending on how the monitor scales. Unfortunately if the manual doesn't specify, there is no way to determine what resolution the monitor is scaling to without trial and error. It's likely something simple such as 1920x1080 to simulate a 1080p monitor because that would be the most obvious choice. You can verify by changing the active resolution to 1920x1080 and displaying a checkerboard pixel pattern in an image viewer that can display an image 1:1 without scaling: https://www.monitortests.com/pattern/pat...0x1080.png

Cheers, so crux is with this monitor (assuming DSC won't always be forced), I have two options. Either use the 24 inch mode, and just pick an approximate 4:3 resolution if I am not able to find out the exact resolution (I am asking on live chat, they have no clue what im talking about lol), or do the double scaling method you've mentioned with the centering options. Really appreciate the help mate, got one final question, will the double scaling (scaling in general) add any degree of input latency? Presumably with such a high end monitor combined with a 5080, I would not see any noticeable latency or lag?

[ToastyX]

GPU scaling doesn't lag. Monitor scaling depends on the monitor. Most monitors don't lag when scaling. The ones that do would lag one frame, so around 2 ms at 480 Hz.