Blur Busters Forums

Hello!
As you all know, DisplayPort is the only port supported by G-Sync so far. The problem is that NVIDIA GPUs send the "Limited Range RGB 16-235" color signal when using HDMI or DisplayPort and there is no way to select 0-255 signal. Let me quote a review from pcmonitors for better understanding because English is not my first language:
http://pcmonitors.info/reviews/dell-u2414h

An Nvidia GTX 780 was used on our test system and we tested both DisplayPort and HDMI – with interesting results. When using either DisplayPort or HDMI the GPU sent out the wrong colour signal (‘Limited Range RGB 16-235’ instead of ‘Full Range RGB 0-255’). This reduced gamma, skewed white point, hugely impacted contrast and simply gave everything a washed out look. We are quite used to seeing this with Nvidia GPUs connected via HDMI as that is their default behaviour – treat the connected device as an HDTV. But we aren’t used to seeing this over DisplayPort...

Another very good article:
http://pcmonitors.info/articles/correct ... d-amd-gpus

Despite their issues seeming to be isolated to the 1920 x 1080 (Full HD) resolution at present rather than any resolution, Nvidia GPUs are worse offenders for users with affected monitors. They use a ‘Limited Range RGB (16-235)’ colour signal that completely destroys the image quality of the monitor by hampering contrast, colour vibrancy and shade variety. Unlike on AMD GPUs you can’t simply enable the correct ‘Full Range RGB (0-255)’ colour signal universally with a simple drop-down option, either. To add insult to injury a minority of monitors act this way over DisplayPort as well, despite that being a PC only connection where the GPU treating the monitor as a TV simply doesn’t make sense.

Same thing is mentioned here: http://www.tftcentral.co.uk/reviews/dell_u2414h.htm
Here is a couple of comparisons of Limited Range vs Full Range made by neogaf users:
Limited: http://i.imgur.com/aano8.jpg
Full: http://i.imgur.com/fdnQM.jpg

Limited: http://www.abload.de/img/untitled197dhv.png
Full: http://www.abload.de/img/untitled23xiqs.png

Source: http://www.neogaf.com/forum/showthread. ... 695&page=2

As you can see, difference is huge. I've read discussions on the internet and people claim the reason why GeForce sends wrong color signal is because a monitor sends wrong EDID info to the GPU - instead of asking for 0-255 range it asks for 16-235. As the result, monitor is detected as HDTV. So, it looks like a problem is on BenQ side. Pcmonitors mention this in their Dell 2414 review:

The native resolution of the monitor (1920 x 1080) is listed under ‘Ultra HD, HD, SD’ as ‘1080p, 1920 x 1080 (native) when connected by DisplayPort. This list of resolutions is designed for output in RGB 16-235 to devices such HDTVs. The resolution should instead be listed under ‘PC’ as ‘1920 x 1080 (native)’, but it isn’t.

Of course, NVIDIA could add an option to the driver to select color range like AMD did 5 years ago, but for some reason they don't do that. It is surprising because this problem has been discussed on multiple forums may-many times for more than 5 years. There is an option in NVIDIA driver that allows to select color range but it works only for video, not games or 3D apps! http://i.imgur.com/SqAlcXS.jpg



I wrote this post because I wanted to discuss this problem and ask a question: will I be able to play in Full Range RGB 0-255 on BenQ 2420G/2720G with G-Sync? I really want to buy 2420G but I am afraid I'll have to play in 16-235 with washed out colors. I think this problem is worth reporting to BenQ. Even if the problem is not on their side, maybe they can add some kind of tweak to the monitor settings that will make GPU send 0-255 signal because it looks like NVIDIA is not going to fix anything.

Thank you for reading this wall of text, I hope I don't sound impolite

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

This is weird. Why would NVidia do this?

RealNC wrote:This is weird. Why would NVidia do this?

There probably is a good reason somewhere, but one that needs to be explained fully, and an option to adjust (even if as a hidden adjustment).

Chief Blur Buster wrote:

RealNC wrote:This is weird. Why would NVidia do this?

There probably is a good reason somewhere, but one that needs to be explained fully, and an option to adjust (even if as a hidden adjustment).

It's still incomprehensible to me. Washed out colors? There could be a reason, but not a good one. Not by any stretch of the imagination. Having a crappy picture warrants a refund, even.

Currently the only G-Sync monitor out right now is a VG248QE that has a kit slapped on. Could this be a problem just to that monitor or is this something driver side that will affect all the G-Sync monitors once they are released?

...............wow
i'd imagine that this would be flagged and fixed earlier
I've always thought that 16-235 would look obvious and that people would be complaining all over the place about it due to that...

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.

TSM wrote: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.

If you set a game to run in a particular frequency, it'll only refresh up to that frequency, even in gsync mode. I didn't know you could set a particular frequncy for any given game. As I understand it, there is only "let application decide" or "highest available".

Actually you are correct, but using anything that isn't explicitly 60 hz will override this problem. Just being in G-Sync mode should prevent this from happening since it's variable refresh rate.

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.