2 Bronze

m15 R3, 30Hz to LG C9 120hz monitor, G-Sync

Hi, so my laptop arrived today (super impressed). There are 3 video output options:
DP 1.4
Thunderbolt 3
HDMI 2.0

My LG C9 TV and can handle 120Hz but only has HDMI I think.....in any case I wish to enable G-Sync. It sounds to me Thunderbolt is the best lead but can it handle G-Sync? I know DP already does but wanted to check here first with you awesome guys.

Also I plan to buy a 240Hz monitor in addition too to make full use of the refresh on offer.

thanks

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19 Replies
7 Gold

Re: m15 R3, 30Hz to LG C9 120hz monitor, G-Sync

@Carl1978  G-Sync has two key requirements.  First, you have to be using DisplayPort (or USB-C/TB3, which uses DisplayPort for video traffic).  And second, you have to be using a port that is wired directly to the system's NVIDIA GPU.  On every Dell system I've seen, the USB-C/TB3 port is wired to the Intel GPU, and the NVIDIA GPU only accelerates content on displays attached that way via NVIDIA Optimus, which means it acts as a "render-only" device that passes completed video frames to the Intel GPU.  That has some battery life advantages, but it prevents using G-Sync, as well as Adaptive V-Sync, VR, stereoscopic 3D, and some other technologies.

However, I believe on that system that the Mini-DP output is wired directly to the NVIDIA GPU, in which case that would be the preferable output.  If you want to verify, connect a display to whichever output(s) you want to test, then open NVIDIA Control Panel and go to the PhysX Configuration section.  In there you'll see a diagram showing which GPU controls each active display.  See how it looks when you have displays connected various ways.

1 Copper

Re: m15 R3, 30Hz to LG C9 120hz monitor, G-Sync

So, I´m <Profanity removed>.

 

https://gyazo.com/ab08b428cb91e7b81bcc698acc14599d

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Re: m15 R3, 30Hz to LG C9 120hz monitor, G-Sync

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7 Gold

Re: m15 R3, 30Hz to LG C9 120hz monitor, G-Sync

@Carl1978  Ok, building on the above, it appears that the 2019 LG OLED models are "G-Sync Compatible" displays, and since they appear not to have any DisplayPort inputs, it appears that NVIDIA has done something to get this running over HDMI.  In that case, if you run the test I mentioned above and find that your HDMI output is wired to your NVIDIA GPU (which seems likely on that system since Dell might have done that to support running HDMI-based VR headsets), then I'd connect via HDMI.  If not, then if you're trying to run high refresh rates, you might have to get an active Mini-DisplayPort to HDMI 2.0 adapter.  The less common passive Mini-DisplayPort to HDMI adapters and cables won't run HDMI 2.0, to my knowledge.  The issue with them is that they rely on the source DisplayPort output supporting "Dual Mode DisplayPort", which allows a DisplayPort output to fall back to native HDMI signaling.  The problem is that DisplayPort existed long before HDMI 2.0 did, so I don't know if that capability will allow the source to send (and therefore the adapter/cable to carry) an HDMI 2.0 signal.  By comparison, an active adapter involves the source system sending a native DisplayPort signal to the adapter and then the adapter converts it to HDMI 2.0.

Also, according to this NVIDIA article, you can only run 120 Hz when you're using QHD resolution.  With 4K you'd be limited to 60 Hz.  That's a limitation of HDMI 2.0 itself.  But that article might help you get everything set up.

7 Gold

Re: m15 R3, 30Hz to LG C9 120hz monitor, G-Sync

@Carl1978  Sorry for the triple post here, but this G-Sync support over HDMI in order to operate with these LG TVs came as news to me.  Detailed technical information seems to be scarce, but the articles I've read indicate that a) you are supposed to use the HDMI output on your GPU to use G-Sync with these TVs, and b) this capability is only available with RTX GPUs and GTX 16 Series GPUs.  That's interesting for two reasons.

First, G-Sync in the past only worked over DisplayPort and required the display to have a proprietary G-Sync control board containing pretty powerful components.  Additionally, second, G-Sync has been supported on GeForce GPUs going back well before the RTX and GTX 16 Series GPUs.

So my GUESS here is that the G-Sync in this particular case of the LG OLED TVs isn't the "normal G-Sync" that involves NVIDIA proprietary technology, but rather HDMI VRR or something very much like it.  That might explain both why this LG OLED use case works over HDMI and why it's only possible on NVIDIA's latest GPUs.  But that may also mean that G-Sync to an LG OLED might be possible ONLY from an actual HDMI source port wired directly to the NVIDIA GPU, i.e. the Mini-DisplayPort output might not be usable for G-Sync to an LG OLED TV no matter what type of adapter/cable you use.  So hopefully your HDMI output is wired to the NVIDIA GPU.

As for the 240 Hz display you're considering purchasing, if it supports G-Sync, chances are it will be "normal G-Sync" that operates over DisplayPort, in which case connect it to the Mini-DisplayPort output.

2 Bronze

Re: m15 R3, 30Hz to LG C9 120hz monitor, G-Sync

What an absolutely amazing response you have posted!  Honestly I cant thank you enough for this, please have 10x digital drinks on me and very much appreciated kudos!!

https://gyazo.com/1eb6a54af3d1594b1199654dbd90a783 - here is the screenshot I took of the config I have so far; couldn't quite see the video card showing the connections but does appear to show the Super card linked to the LG via hdmi, which I know is working fine as I just extended my display to it and its been hitting buttery smooth 120fps on ultra settings which then dropped to around once I enabled RTX.....and wow, I am absolutely blown away by this level of gaming!!  RTX is breathtaking, and then all the water droplets and little touches (testing on Shadow of Tomb Raider).

So I have the frames sorted which is lovely, the couple of questions I would have then if I may:

1)  How can I tell if G-sync is working or not?  The laptop I bought, I went for the 300hz one simply because I didn't see the point on getting the 144hz proper g-sync one, I don't see much value in gaming on 15inch vs 55......I did see in the spec that the super cards can output g-sync, I vaguely recall this being via DP though so this is very interesting if its via HDMI.  The hdmi port is actually hdmi 2.1 also, I've read that had I bought the LG CX then id be able to get 4k 120fps via 2.0 as it drops to 4:2:0 colour data (I think).  

2)  Is it possible to game in 2k at all at over 100fps?  Anything outside of 1080 is only showing 60hz, for example 3840 x 2160 is 60hz.  If I look to 2k, 2560 x 1440 its only hitting 30hz.  Ideally I could push for 2k and still hit over 100fps, strange how it would goto 4k and offer 60hz.....

As for the other monitor, a DP 1.4a to hdmi 2 will probably be fine, although.....TB3 would have been nice had gsync worked.  Monitor wise I've managed to find a real 10bit one too, which seems to be a rarity https://www.amazon.co.uk/Gigabyte-Aorus-FI27Q-P-Gaming-Monitor-165Hz/dp/B07ZHLBPMV

I'm so excited by all of this.....the gaming experience I just saw then was mind blowing, I mean I've got the Xbox X, the Nvidia shield with geforcenow, I've testing ultra settings before but its capped at 60fps and I'm not sure why but this seems leagues above the geforcenow experience!  No way will I be using that again 

I'm very much new but keen to learn......I notice there are a lot of settings too which is a little confusing ranging from the nvidia settings to the ingame settings.....

I suffer from eye strain, but need to take care of eye comfort which is why Ive invested in better screen tech, ie there is no colour dithering going on anywhere, the LG is a pure 10bit panel, my laptop is 100% sRGB, there isn't much more I can do, but all that aside I feel like a kid in a candy shop, all I need to do now is learn to code and I'll be away!

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2 Bronze

Re: m15 R3, 30Hz to LG C9 120hz monitor, G-Sync

Okay so this has become more interesting! :). 

https://gyazo.com/d73573a970bd22ea118e1251c0f7f833 - so I selected a 4k display, it then did something really funky and switched back to laptop/LG screens on at the same time, duplicate mode, but the laptop was all purple tinge.  Then I noticed the g-sync options appeared and was labelling the LG monitor differently, now it will allow me to select 4k at 60hz, but gsync is enabled so at least I will know that's working.  Just puzzled to why there isn't a 2k option better than 30hz...and quite amazed this is all working over hdmi so far.

https://gyazo.com/01c8e008012167a0f7d0517b8d78e367 here is the gsync options
if I have the laptop only this is the only resolution you can get https://gyazo.com/8f823e283bfbebe8b090b0733f1cb5fc

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7 Gold

Re: m15 R3, 30Hz to LG C9 120hz monitor, G-Sync

@Carl1978  It seems you wrote another reply while I was posting my own.  I'm not sure why you're limited to 30 Hz when selecting QHD, particularly as the NVIDIA article I linked that specifically deals with your TV suggests that you should be able to run 120 Hz.  Maybe confirm you're running the latest firmware and NVIDIA drivers?

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7 Gold

Re: m15 R3, 30Hz to LG C9 120hz monitor, G-Sync

@Carl1978  Just saw that other screenshot too.  QHD (2560x1440) isn't even listed in your resolution choices, at least not within the portion of the list that's visible in your screenshot.  2560x1600 is, but that's not the same thing.  However, comparing that against the screenshot in the NVIDIA article I linked, 2560x1440 is at the very bottom in the PC resolution section, not the "UltraHD,HD,SD" section.  So maybe scroll down your resolution list to see if you have 2560x1440 at the very bottom somewhere.  And if you do, see if you can enable 120 Hz.

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