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Trying to add 1080p 48Hz.
12-08-2021, 05:23 PM
Post: #1
Trying to add 1080p 48Hz.
Hi,

My very first post here. I'm trying to add a 48Hz mode for watching 24FPS content. My monitor is an Asus VH222T connected via dual-link DVI (I believe) and right now I don't have any GPU hence running the system on integrated HD2000 graphics (i3-2100).

Here are the supported timings of my monitor:

https://i.imgur.com/3hqyl0T.png

   

Here, I'd like to mention that I know next to nothing about monitors and have no idea what "H(KHz)" and "Pixel(MHz)" means so I'd truly appreciate it if someone would explain the procedure to me in complete layman's terms!

Also, if you are aware of a video tutorial that explains all these monitor related terms then kindly link it here as well.

Thanks in advance.
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12-09-2021, 02:29 AM
Post: #2
RE: Trying to add 1080p 48Hz.
Horizontal scan rate (kHz) is the number of lines per second including blanking.
Pixel clock (MHz) is the number of pixels per second including blanking.
Blanking is the period between each line and frame.
Here are some other terms: https://www.monitortests.com/blog/timing...explained/

CRU can fill in the timing parameters for you, so try the timing presets first. The monitor might not accept 48 Hz. 72 Hz is more likely to work. Intel GPUs only have single-link DVI, and that monitor only uses single-link DVI anyway, so the driver will ignore resolutions beyond 165 MHz pixel clock. "Exact reduced" timing will keep the pixel clock under 165 MHz for 1920x1080 @ 72 Hz. If that doesn't work, you might have to increase the horizontal blanking. You'll have to play around and see what works. Timing standards are pretty arbitrary, so they're not important as long as it works.
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12-09-2021, 06:31 AM
Post: #3
RE: Trying to add 1080p 48Hz.
(12-09-2021 02:29 AM)ToastyX Wrote:  Here are some other terms: https://www.monitortests.com/blog/timing...explained/

CRU can fill in the timing parameters for you, so try the timing presets first. The monitor might not accept 48 Hz. 72 Hz is more likely to work. Intel GPUs only have single-link DVI, and that monitor only uses single-link DVI anyway, so the driver will ignore resolutions beyond 165 MHz pixel clock.

I didn't realize my monitor was only single-link and since I'm limited to 165 MHz pixel as a result; what if I make a custom resolution at 900p?

As per the user manual; my monitor supports a horizontal frequency of 67.5KHz @ 1920x1080p (60Hz) and if I force it in CRU with a resolution of 1600x900; the refresh rate goes up to 71.961Hz; whereas pixel clock drops down to 130MHz:

   

Is this how it's supposed to work? And also; can I force a 40Hz vsync in games as the monitor supports 45.481KHz @ 1280x720 (60Hz) and when I convert it to 1080p it comes at 40.681Hz.

   

As you can tell; I'm a total noob so any input would be appreciated. The reason I want 40Hz vsync is because, as you can tell, my hardware is extremely weak, although I'll (hopefully) be adding a GT1030 in the future.

Thanks for your time!
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12-09-2021, 04:06 PM
Post: #4
RE: Trying to add 1080p 48Hz.
You're overcomplicating this. The manual only lists the rates for each resolution, not what it actually supports. Forget the manual. Just add 1920x1080 @ 72 Hz with "Exact reduced" timing. If the monitor won't accept that, try increasing the horizontal blanking to 120. That's still under 165 MHz pixel clock. As I said, the monitor might not accept 48 Hz, so it probably won't accept 40 Hz, but you can try anyway. The lowest is probably 50 Hz.
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12-09-2021, 05:49 PM
Post: #5
RE: Trying to add 1080p 48Hz.
(12-09-2021 04:06 PM)ToastyX Wrote:  You're overcomplicating this. The manual only lists the rates for each resolution, not what it actually supports. Forget the manual. Just add 1920x1080 @ 72 Hz with "Exact reduced" timing. If the monitor won't accept that, try increasing the horizontal blanking to 120. That's still under 165 MHz pixel clock. As I said, the monitor might not accept 48 Hz, so it probably won't accept 40 Hz, but you can try anyway. The lowest is probably 50 Hz.

You're absolutely right; I'm probably looking too deep into things. It's just that I suffer from ADHD with hyper-focus behavior which means I try to find a pattern into everything, just to connect all the dots.

In any case; I shall try to set the parameters you described once I get back home. Truly appreciate the help!
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