Low resolutions with 3070Ti not possible? It was working fine with 2070

[Rochabian]

My PC is plugged in a Multisync CRT
Before i change my graphics card to a 3070Ti, i was using a 2070 with a DP to VGA adapter and CRU and i was able to display resolutions from 320x240 to 1280x1024 fine.
Now i've switched to a 3070Ti, with same adaptator and CRT, and i can't get resolutions below 480p, or they are corrupted (bad sync). I use the same CRU profile
Custom resolutions appears and i can select 320x240 with quickres but the display is corrupted, bad vsync i think, it's unreadable

I've tried to patch the driver for limits but it's the same.

Is there a low pixel clock limit on NVIDIA 3000 series ?

Any idea how i can force 320x240 like it was with the 2070

I've disabled DSR and set no scaling to screen in NVIDIA panel (as it was with my 2070 ) but it still doesn't work with the 3070ti

[ToastyX]

I thought the minimum pixel clock was 25 MHz. Increasing the blanking should make it possible to reach 25 MHz. If there's an issue specifically with lower resolutions and it's not a pixel clock limit, then it might be a driver bug.

[Rochabian]

(08-17-2022 08:10 PM)ToastyX Wrote:  I thought the minimum pixel clock was 25 MHz. Increasing the blanking should make it possible to reach 25 MHz. If there's an issue specifically with lower resolutions and it's not a pixel clock limit, then it might be a driver bug.

No pixel clock limit for 2070 because i was able to do 320x240@60
Perhaps a driver bug and low res broken in 3000 series
I've asked NVIDIA about this, i should have an answer soon

[Rochabian]

Is nvidia patcher able to remove low pixel clock limit ?
I've tried it but it's the same;
You say that you thought there was a 25Mhz pixel clock limit. Is it for the 3000 series or all Nvidia cards ? Because with a 1070 & 2070 320x240@60 was working fine

[ToastyX]

Is there a pixel clock limit or is it a resolution issue? I don't know anything about the 3000-series. I thought there was a 25 MHz minimum for digital signals on all cards, but maybe that was only AMD.

[Rochabian]

I think this is a pixel clock limit as i can't go below 640x350 (25Mhz)
It seems that my 2070 was a bit special because some users says that it shoudn't be possible to go under 25Mhz with RTX 2000 series too, that's why they use "super-resolutions". I've been lucky with this ASUS 2070 DUAL, it has a DVI output, perhaps that's why it works at low res whenever i use the DP port with a DP to VGA converter. I've put this gem back in my arcade cab.....
What can i do for the RTX 3000 and low pixel clock instead of using "super resolutions" (for example 3200x240@60) ?
This low pixel clock can't be removed at all with software patch, i assume ?

EDIT : I've seen that the ATI patch remove low-res limit, what about NVIDIA, it isn't possible ?

[ToastyX]

The AMD/ATI limit was for custom resolutions with AMD's software, which didn't affect CRU. That was not a pixel clock limit.

I don't know if it's possible to patch the limit. My GTX 1060 doesn't seem to be affected, so I don't have a way of testing it. I tried looking for values that could represent 25 MHz in the driver but didn't find anything near the other limits. Considering you can add and select the resolution, that means the driver isn't filtering it out, so it might actually be a hardware imposed limitation. The only way to raise the pixel clock without changing the resolution is to increase the blanking, if the display can handle that.

[Rochabian]

Ok thanks for the explanation, as you said it must be a hardware limitation of the digital signal output, as RTX 2000 and beyond doesn't have any analog port. My 2070 card is probably the last recent one wich accept low pixel clock, it's the only model with DVI output i've seen so far.
As my CRT is able to display from 240x240 to 1280x1024, i think i can test 1280x240@100 or@120, it will be above the 25Mhz limit, keeping the 240 lines for sharp scanlines.
BTW, thanks for CRU 1.52, i can add even more modelines on my NVIDIA card with extensions blocks !

Thanks for all

[Rochabian]

Another thing, does Intel Integrated Graphics has a low pixel clock limit ?
If not i can passthrough the 3070 to the integrated graphics to have low resolution ?

[ToastyX]

I haven't tested Intel.