LG C9 underclocking to 96Hz

Talk about overclocking displays at a higher refresh rate. This includes homebrew, 165Hz, QNIX, Catleap, Overlord Tempest, SEIKI displays, certain HDTVs, and other overclockable displays.
Post Reply
nrv
Posts: 5
Joined: 13 Oct 2022, 16:54

LG C9 underclocking to 96Hz

Post by nrv » 13 Oct 2022, 16:58

Hi,
I managed to make my nvidia 3DVision kit work with my LG C9 at 100Hz using CRU and NvTimingsEd.
I tried to watch my 3D bluRays on my C9, but although 3D is very good, I have got judder.
My videos are 23.976Hz. With 3DVision at 100Hz, each eye is at 50 frames/second.

So I created a 96Hz profile with CRU. It seems to work sucessfuly with windows desktop.
On the tv, the HDMI Diagnostics menu indicates : 95.91Hz.
testufo refreshrate indicates 95.994Hz.

But 3D doesn't work anymore at 96Hz : the image on the TV flickers (image does not flicker at 100Hz).
So I checked for frames drops with testufo frameskipping. And indeed I've got frames drops at 96Hz, whereas I don't at 100Hz.

For 120Hz, my CRU settings are :
Horizontal : Active=1920, Front proch=88, sync width=44, Total=2200
Vertical : Active=1080, Front proch=4, sync width=5, Total=1125

For 96HZ, my CRU settings are :
Horizontal : Active=1920, Front proch=638, sync width=44, Total=2750
Vertical : Active=1080, Front proch=4, sync width=5, Total=1125
That should result in a 297MHz pixel clock, just as with the 100Hz settings.

Any idea to make my TV work at 96Hz ?

User avatar
Chief Blur Buster
Site Admin
Posts: 10731
Joined: 05 Dec 2013, 15:44
Location: Toronto / Hamilton, Ontario, Canada
Contact:

Re: LG C9 underclocking to 96Hz

Post by Chief Blur Buster » 13 Oct 2022, 17:05

Better to use Quick Frame Transport aka QFT (ToastyX Vertical Total Calculator) and modify the 120Hz signal to transmit a 96Hz refresh cycle in 1/120sec.

- Completely unchanged horizontal numbers
- Perfectly exactly the same Horizontal Scan Rate as 120Hz
- Perfectly exactly the same Pixel Clock as 120Hz
- Turn on VRR on the panel.

Then you create a fixed-Hz 96Hz signal that is like a perma-96fps-capped 120Hz VRR signal, in a non-VRR signal wrapper, in a custom EDID.

TL;DR: You have to get away from 1125 and the QFT signal will have a Vertical Total of very roughly approximately 1125*(120/96) instead of 1125. Keep the same horizontals, and only modify one of the verticals -- usually only the Back Porch

See if this works!

The frameskipping should hopefully disappear.
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on Twitter
To support Blur Busters - see Multiple Lists of Best Gaming Monitors
Forum Rules wrote:  1. Rule #1: Be Nice. This is published forum rule #1. Even To Newbies & People You Disagree With!
  2. Please report rule violations If you see a post that violates forum rules, then report the post.
  3. ALWAYS respect indie testers here. See how indies are bootstrapping Blur Busters research!

nrv
Posts: 5
Joined: 13 Oct 2022, 16:54

Re: LG C9 underclocking to 96Hz

Post by nrv » 13 Oct 2022, 17:40

Thanks for that fast answer, and congratulations for your website and this forum !

I thought to that VRR option too. But unfortunately my graphics card (Titan X pascal) only has a HDMI 2.0b port. I guess that's the reason why I don't see any VRR option on the TV. Even with a Displayport->hdmi 2.1 active adapter I should not be able to use VRR.

I will check "Quick Frame Transport aka QFT (ToastyX Vertical Total Calculator)".
Thanks.

nrv
Posts: 5
Joined: 13 Oct 2022, 16:54

Re: LG C9 underclocking to 96Hz

Post by nrv » 16 Nov 2022, 17:15

I made a lot of tests using different parameters, including Quick Frame Transport (Interesting technics by the way)
But I did not managed to find working parameters for 96Hz.
I mean windows looks OK at 96Hz, but TestUFO always indicates dropped frames (TestUFO is OK when frequency is 100Hz or 120Hz).
TV HDMI diagnostics sometimes indicates errors, but not always, depending on the resolution parameters.

Using the 1080p100 resolution from the TV as a start point, I tried :
- Just decrease frequency from 100Hz to 95.905Hz
- Increase horizontal porch from 528 to 638 pixels and keep pixel clock at 297MHz.
- Increase vertical porch from 1125 to 1173 lines and keep pixel clock at 297MHz (QFT technics).

I also tried the 1080p120 resolution from the TV as a start point and increase vertical porch from 1125 to 1407 lines, but screen remained black.

I made the tests with those parameters on the TV :
- HDMI Ultra HD Deep Colour ON
- HDMI Gaming Instant Response ON and OFF
- HDMI Source Type defined as PC and Console

I did not find a VRR setting on the LG C9, but according to this forum, that parameter does not exist on the TV side.
https://www.reddit.com/r/OLED_Gaming/co ... _an_lg_c9/


I ordered the Club3D CAC-1085 displayport 1.4 to hdmi 2.1 adapter, and managed to get 4K 120Hz HDR working with those parameters :
Horizontal Front Porch : 48, Sync width : 32, Total pixel : 3970
Vertical Front Porch : 21, Sync width : 23, Total pixel : 2255

I re-checked my custom resolutions using this adapter at 1080p and 4K.
TestUFO frameskipping is OK at 120Hz and 100Hz but always indicates dropped frames at 96Hz.
Attachments
TestUFO indicates frame drops.jpg
TestUFO indicates frame drops.jpg (36.95 KiB) Viewed 1116 times

User avatar
Chief Blur Buster
Site Admin
Posts: 10731
Joined: 05 Dec 2013, 15:44
Location: Toronto / Hamilton, Ontario, Canada
Contact:

Re: LG C9 underclocking to 96Hz

Post by Chief Blur Buster » 17 Nov 2022, 00:09

nrv wrote:
16 Nov 2022, 17:15
I re-checked my custom resolutions using this adapter at 1080p and 4K.
TestUFO frameskipping is OK at 120Hz and 100Hz but always indicates dropped frames at 96Hz.
Duplicated frames. Brighter squares = repeated refresh cycles.

It looks like 120Hz creating a 1:1:1:2 pulldown effect.

Damn, it's too bad that the older C9 doesn't work with this. The QFT trick is more compatible with VRR panels, so VRR-free panels are far less likely to work with QFT fixed-Hz 96Hz.

This works much more successfully on newer OLEDs with VRR turned on.
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on Twitter
To support Blur Busters - see Multiple Lists of Best Gaming Monitors
Forum Rules wrote:  1. Rule #1: Be Nice. This is published forum rule #1. Even To Newbies & People You Disagree With!
  2. Please report rule violations If you see a post that violates forum rules, then report the post.
  3. ALWAYS respect indie testers here. See how indies are bootstrapping Blur Busters research!

nrv
Posts: 5
Joined: 13 Oct 2022, 16:54

Re: LG C9 underclocking to 96Hz

Post by nrv » 17 Nov 2022, 15:47

But yet the C9 is compatible with VRR.

https://www.rtings.com/tv/reviews/lg/c9-oled
1080p VRR Maximum 120 Hz
1080p VRR Minimum 40 Hz

It's even compatible with gsync on GeForce RTX or GeForce GTX 16-Series GPU. Unfortunately my graphics card is older so I can't test this.
https://www.nvidia.com/en-us/geforce/ne ... lable-now/

It seems there is no menu command on the TV side to activate VRR, you just need to activate it on the connected compatible device.

Does the "VRR compatible device" send a special command to the TV to activate VRR ?
If that's the case, I'm dreaming of a tool to do that, just like ToastyX Strobelight did the trick to activate lightboost on my VG278H screen.

User avatar
Chief Blur Buster
Site Admin
Posts: 10731
Joined: 05 Dec 2013, 15:44
Location: Toronto / Hamilton, Ontario, Canada
Contact:

Re: LG C9 underclocking to 96Hz

Post by Chief Blur Buster » 18 Nov 2022, 18:33

nrv wrote:
17 Nov 2022, 15:47
Does the "VRR compatible device" send a special command to the TV to activate VRR ?
If that's the case, I'm dreaming of a tool to do that, just like ToastyX Strobelight did the trick to activate lightboost on my VG278H screen.
I checked, and you're right, if you follow these steps:

1. Upgrade to latest C9 firmware. Early C9 firmware do not support VRR.
2. Please turn on "Instant Gaming Response" to get the hidden VRR menu option to appear.
3. Then turn VRR on in the television menu.
4. Try again with the latest ToastyX CRU that contains the "Vertical Total Calculator".

Some VRR implementations are 2-way and some VRR implementations (generic VESA Adaptive Sync) is 1-way only.

You can have ToastyX CRU trick a display into VRR mode on AMD Radeon card HDMI output.

That's how some people got VRR working on old Multisync CRT tubes too (via HDMI->VGA converters).

Unfortunately this is not something NVIDIA GPUs seem to be able to do (force blind VRR output). But if you follow steps 1-4, then the problem is solved.

Don't forget you need to use Vertical Total Calculator, not manually editing vertical totals. You must modify a working 120Hz mode to get your 96Hz via editing the refresh rate ONLY, in the new "Vertical Total Calculator" setting of ToastyX CRU.

To simulate a perma-frame-capped VRR mode as a non-VRR custom mode via ToastyX CRU (e.g. 120Hz VRR with a permanent 96fps cap = fixed Hz 96Hz), you must never never never edit any number in ToastyX except for refresh rate WHILE also in "Vertical Total Calculator" mode WHILE viewing a working refresh rate (e.g. 120Hz). The topology of the video signal is actually identical!

(basically a 96Hz signal that looks identical to a 120Hz VRR signal with a permanent 96fps cap, but as an EDID! No RTSS needed, no frame cap needed, the television becomes the "VRR framerate cap" via a hacked fixed-Hz signal)

This is the most VRR-compatible fixed-Hz mode for non-VRR GPUs. The televisions' VRR support must be enabled in order for a custom fixed-Hz 96Hz "Vertical Total Calculator" mode to function in a non-frameskipped manner.
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on Twitter
To support Blur Busters - see Multiple Lists of Best Gaming Monitors
Forum Rules wrote:  1. Rule #1: Be Nice. This is published forum rule #1. Even To Newbies & People You Disagree With!
  2. Please report rule violations If you see a post that violates forum rules, then report the post.
  3. ALWAYS respect indie testers here. See how indies are bootstrapping Blur Busters research!

nrv
Posts: 5
Joined: 13 Oct 2022, 16:54

Re: LG C9 underclocking to 96Hz

Post by nrv » 20 Nov 2022, 16:00

>> 1. Upgrade to latest C9 firmware. Early C9 firmware do not support VRR.
Already done : 05.30.11

>> 2. Please turn on "Instant Gaming Response" to get the hidden VRR menu option to appear.
Already done : "Instant Gaming Response" is ON.
"Ultra Deep Colour" is ON too, as some forums tell to switch this OFF then ON again to activate VRR. I tried but no VRR with that either.

>> 3. Then turn VRR on in the television menu.
I don't have a hidden VRR menu option.
Please where did you read about it ? All that I've found is people telling there is no such option on the tv, and that is automated when the source is vrr ready.

>> 4. Try again with the latest ToastyX CRU that contains the "Vertical Total Calculator".
Already done. I used the CRU "Vertical Total Calculator". to get the 96Hz
I followed your instructions from here : viewtopic.php?t=10402
(Very clear, thank you for that tutorial)

So it gave me those parameters :

Original TV resolution parameters
Refresh rate 100
Resolution 1920 1080
Front Porch pixels 528
Sync width pixels 44
Total pixels 2640
Front Porch lines 4
Sync width lines 5
Total lines 1125
Pixel Clock 297
I changed Refresh rate to 95.904, and CRU Vertical Total Calculator changed Total lines to 1173


I also tried the 120Hz resolution as a starting point :
Refresh rate 120
Resolution 1920 1080
Front Porch pixels 88
Sync width pixels 44
Total pixels 2200
Front Porch lines 4
Sync width lines 5
Total lines 1125
Pixel Clock 297
I changed Refresh rate to 95.948, and CRU Vertical Total Calculator changed Total lines to 1407


>> You can have ToastyX CRU trick a display into VRR mode on AMD Radeon card HDMI output.
You mean that using the previous resolution modified by CRU Vertical Total Calculator would work on AMD Radeon card ? The tv would automaticaly understand it is VRR ?

>> Unfortunately this is not something NVIDIA GPUs seem to be able to do (force blind VRR output). But if you follow steps 1-4, then the problem is solved.
I can't follow step 3 : Then turn VRR on in the television menu.
Attachments
LatestDriver.jpg
LatestDriver.jpg (38.09 KiB) Viewed 894 times
Instant Game Response ON.jpg
Instant Game Response ON.jpg (45.13 KiB) Viewed 894 times
Ultra Deep Colour ON.jpg
Ultra Deep Colour ON.jpg (48.63 KiB) Viewed 894 times

User avatar
Chief Blur Buster
Site Admin
Posts: 10731
Joined: 05 Dec 2013, 15:44
Location: Toronto / Hamilton, Ontario, Canada
Contact:

Re: LG C9 underclocking to 96Hz

Post by Chief Blur Buster » 22 Nov 2022, 18:28

Oh, right, I forgot -- "Instant Gaming Response" automatically turns VRR on. That's the setting.

Can you retry with 4K modes?

(modify from standard EDID 4400x2250 Totals instead of 2200x1125 Totals)

I suspect the 4K OLEDs don't like VRR at 1080p. Not 100% sure.

If you can't do 4K 120Hz even at 4:2:2 chroma with Deep Color turned OFF (e.g. older Intel GPUs), try upgrading your GPU.

4K 60Hz 4:4:4 Deep Color is approximately similar bandwidth as 4K 120Hz 4:2:0 Non-Deep Color (8bpc), so you may have to wedge some cable bandwidth headroom by roughly halving bits per pixel. Not all GPUs will automatically switch bits per pixel, so your configurability may be limited. But you can force things somewhat from the TV side by turning off all kinds of enhanced pixel color options, to "help out" the ability of doing 4K 120Hz.

Another trick is to try to enter a FreeSync Range to your Intel GPU in an EDID override (CEA861 extension block in ToastyX CRU), even if NVIDIA refuses to support it, and see if that tricks the panel into the right mode. Another trick is to simply create a 96Hz QFT FreeSync mode (you can combine QFT and VRR into the same mode), and just treat it as a fixed-Hz 96Hz mode.

Now that being said, you may have to upgrade your GPU to a GPU that supports VRR before it works... There may be something preventing it from working.
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on Twitter
To support Blur Busters - see Multiple Lists of Best Gaming Monitors
Forum Rules wrote:  1. Rule #1: Be Nice. This is published forum rule #1. Even To Newbies & People You Disagree With!
  2. Please report rule violations If you see a post that violates forum rules, then report the post.
  3. ALWAYS respect indie testers here. See how indies are bootstrapping Blur Busters research!

Post Reply