G-Sync Monitors and Limited Range RGB 16-235 on NVIDIA GPUs

[fenderjaguar]

I was confused because there are games that run at 60 hz but are still in full 144 hz G-Sync mode (Diablo 3 for example). I checked one of the Sonic the Hedgehog games and you are correct. Using application controlled causes the maximum refresh rate to lock to whatever the program dictates. Luckily application controlled is only necessary when a game's speed is dictated by the refresh rate.

Usually, it's the frame rate cap which the game uses at engine level, not the refresh, which dictates the speed. For example, RAGE is capped at 60 fps, and therefore will run at 60hz because of g-sync. But you wouldn't want to run it in 60hz mode, if you know what I mean? It wants to be capped under the refresh because of the vsync type input lag that seems to occur when the hz maxes out, within a particular refresh rate. So you want to be capped under it. It wouldn't matter if you were running in 85hz, 100hz, 120hz or 144hz, just as long as it's over 60hz, even though it will be running in 60hz mode because of the frame rate.

Are you talking about sonic transformed? because I know how to get this game running perfectly with G-sync, but you need to switch vsync on in the config, force highest refresh from driver level, then cap the frame rate at 60 fps with dxtory or rivatuner statistics server (rivatuner is better, it's more accurate and precisely timed). This case of sonic transformed, will run over 60 fps and stutter like crazy. it doesn't speed up, but it's only meant to be run at 60fps or 30 fps capped. Any other frame rate and it stutters. Funnily enough, they did engine cap at 59 if you disable vsync in the config, and it's pretty stuttery even then, because even though g-sync will start running the monitor at 59hz to match it, the physics is somehow out of key.

Anyway, sorry If I've rambled, or misinterpreted anything you've said...

[TSM]

Most of the Sonic games available on PC have the game's speed dictated by the refresh rate you are running at. Sonic Adventure 2 or Sonic CD for instance will run at normal 1x speed at 60hz (60 FPS). Running at 120hz makes the game run at 2x speed (120 FPS). The speed increase is linear with the refresh rate increase over 60hz. The solution to this is to let the application control the refresh rate. There are many games that have either the game's speed or physics tied to the frame rate which causes issues when raising the refresh rate. Of course you could always use an external program to cap the game like you did with transformed.

[RealNC]

Usually, it's the frame rate cap which the game uses at engine level, not the refresh, which dictates the speed. For example, RAGE is capped at 60 fps, and therefore will run at 60hz because of g-sync. But you wouldn't want to run it in 60hz mode, if you know what I mean? It wants to be capped under the refresh because of the vsync type input lag that seems to occur when the hz maxes out

You do want to run it at 60FPS, because that means it's already capped under the max refresh rate of the monitor, which is 144. You don't need another cap on top of that.

When you cap the framerate with G-Sync, you're trying to avoid the maximum refresh rate that's possible, and that's 144Hz with the Asus monitor. If you go near 144Hz, that's where the input lag comes in and G-Sync behaves like V-Sync. 60FPS means G-Sync drives the monitor at 60Hz. So all is fine.

[fenderjaguar]

You do want to run it at 60FPS, because that means it's already capped under the max refresh rate of the monitor, which is 144. You don't need another cap on top of that.

When you cap the framerate with G-Sync, you're trying to avoid the maximum refresh rate that's possible, and that's 144Hz with the Asus monitor. If you go near 144Hz, that's where the input lag comes in and G-Sync behaves like V-Sync. 60FPS means G-Sync drives the monitor at 60Hz. So all is fine.

That's what I said. I meant you didn't want to run G-sync in 60hz mode, unless it was a game that was already capped under 60 fps anway, like the first Sonic all stars racing (which will only run at 30 fps).

G-sync doesn't just run in 144hz mode. Some games will default at 60hz mode, and that will be the highest refresh you can achieve, even with g-sync enabled, even with no frame rate cap. For example, Doom 3 BFG won't run any higher than 120hz mode, even if you change the engine frame rate cap to be much higher than 120 fps. Even when forcing highest refresh from the driver level. The only way to get it to run in 144hz is with a 1920x1078 style custom resolution, but then g-sync won't run at all with that custom resolution. What I do here is run 120hz g-sync and cap at 110 fps with the config, so that I'm not maxing out the hz and getting just as much input lag as I would be at 120hz vsync.

I didn't mean that RAGE needed capping again, it's already capped at engine level, I just meant it shouldn't be run in 60hz mode

[RealNC]

I didn't mean that RAGE needed capping again, it's already capped at engine level, I just meant it shouldn't be run in 60hz mode

I don't understand. There is no 60Hz mode with G-Sync. The only way to force a 60Hz mode, is to not use G-Sync. If you use G-Sync, and the game is capped to 60FPS, then G-Sync will use 60Hz *most of the time*, but not always; it will go lower when the game stutters from time to time.

[IwantGSYNC]

I know that Adam of pcmonitors.info wanted me to report this issue to NVIDIA too. Let me send this post to my NVIDIA contacts and see if there's any comment.

A workaround/solution for several of us would be nice; even if it has to be a registry tweak, or a hidden adjustment.

Thanks!
Mark Rejhon

Thank you very much! I don't know actually if it is a problem on Nvidia or BenQ side, so it seems to me it is worth contacting them both I also found a pretty interesting post:
http://forums.guru3d.com/showthread.php?t=365034

Right now only samsung HDTV allows Nv card to send correct colors, samsung HDTV has 2'edids. If you rename HDMI input to PC or choose PC HDMI input it will automaticly send 2'nd edid, this 2'nd edid will tell Nv card its connected to PC monitor, not HDTV

If BenQ/other monitor manufacturers implement something like this, it would be awesome. I don't trust Nvidia, they don't seem to care about this problem at all.

Also, maybe it is worth writing a letter to all major tech sites like fudzilla, anandtech, thg, etc (blurbusters have been aware of this issue for a long time, I am sure ). If they write an article about this problem and make NV GPUs look inferior to AMD then maybe Nvidia will start doing something? As far as I know, AMD started to fix frame pacing after an article on thg. I've already started writing a letter but my English is pretty bad so it is better to be done by a native speaker, I guess.

Wait, that link says that if your resolution is listed under "PC" then in the Nvidia Control Panel > Display > Change Resolution then you are getting a full signal. That's where mine is listed. Check there to see if you are affected.

It seems like this problem would specifically affect displays running SD/HD standards: 640x480 60, 640x576 50, 1280x720 at 50/60 and 1920x1080 50/60. G-Sync seems like it specifically corrects this problem. You can use the nvidia control panel to set a game to 60hz but still run it in g-sync mode which refreshes at up to 144hz.

And what about games like Assassin's Creed IV that is limited to 60 fps and runs at 60hz max? For example, I choose 1080p@144hz in Windows settings or control panel, then launch the game, it changes resolution to 1080p@60hz... What happens to color signal? Will it stay at 0-255 or switch to 16-235?

[Chief Blur Buster]

I didn't mean that RAGE needed capping again, it's already capped at engine level, I just meant it shouldn't be run in 60hz mode

I don't understand. There is no 60Hz mode with G-Sync. The only way to force a 60Hz mode, is to not use G-Sync. If you use G-Sync, and the game is capped to 60FPS, then G-Sync will use 60Hz *most of the time*, but not always; it will go lower when the game stutters from time to time.

The GSYNC maximum refresh rate is configurable. I'm able to run GSYNC with a max rate of 60Hz, 85Hz, 100Hz, 120Hz, or 144Hz. There are some uses of using a lower GSYNC max rate; as GSYNC with an 85Hz cap slows down the LCD scanout to 1/85sec instead of 1/144sec, which means better color quality (much like 85Hz has better colors than 144Hz), so it can look good for your games stuck at 60fps, or such. But most of the time, there is little use to running GSYNC less than 144Hz, as that minimizes input lag via faster scanout.

[fenderjaguar]

I didn't mean that RAGE needed capping again, it's already capped at engine level, I just meant it shouldn't be run in 60hz mode

I don't understand. There is no 60Hz mode with G-Sync. The only way to force a 60Hz mode, is to not use G-Sync. If you use G-Sync, and the game is capped to 60FPS, then G-Sync will use 60Hz *most of the time*, but not always; it will go lower when the game stutters from time to time.

Yeah, pretty much what Chief already said. Whilst I understand that G-sync runs in 60hz mode when capped at 60 fps, you can also run G-sync in 60hz mode where 60hz would be your maximum possible refresh.

[fenderjaguar]

But most of the time, there is little use to running GSYNC less than 144Hz, as that minimizes input lag via faster scanout.

So Chief, is there more input lag running capped at 60 fps in 85hz G-sync mode, than there is capped at 60 fps in 144hz G-sync mode?

[Chief Blur Buster]

Yeah, pretty much what Chief already said. Whilst I understand that G-sync runs in 60hz mode when capped at 60 fps, you can also run G-sync in 60hz mode where 60hz would be your maximum possible refresh.

Ideally, you want a maximum refresh above your target framerate, so you don't get input lag from external frame rate capping behaviours.

So Chief, is there more input lag running capped at 60 fps in 85hz G-sync mode, than there is capped at 60 fps in 144hz G-sync mode?

Yes, more Lag for bottom edge of screen, same input lag for top edge. It is all in the scan-out differences.