nVidia G-Sync Q&A with Tom Peterson

Gregster · 24 Aug 2014 at 09:19

So ~2ms when under the monitors refresh rate and ~7ms when over the refresh rate. I can live with that.

http://www.blurbusters.com/gsync/preview2/

Good article there on latency and input lag.

Total Input Lag of Battlefield 4

The game, Battlefield 4, is known to be extremely laggy, even on fast systems. It low 10Hz tick rate ads a huge amount of input lag, and the game rarely caps out at a monitor’s full refresh rate. Battlefield 4 is a game that typically runs at frame rates that benefits immensely from G-SYNC in eliminating erratic stutters and tearing.

Crysis 3

It was good that we were also unable to detect any input lag degradation by using G-SYNC instead of VSYNC OFF. There were many situations where G-SYNC’s incredible ability to smooth the low 45fps frame rate, actually felt better than stuttery 75fps — this is a case where G-SYNC’s currently high price tag is justifiable, as Crysis 3 benefitted immensely from G-SYNC.

Total Input Lag of Counter Strike: Global Offensive

The older game, CS:GO, easily runs at 300 frames per second on a GeForce Titan, so this presents an excellent test case to max-out the frame rate of a G-SYNC monitor. We were curious if G-SYNC monitors started having input lag when frame rates were maxed out at the G-SYNC monitors’ maximum frame rate. We got some rather unusual results, with some very bad news immediately followed by amazingly good news!

At first, it was pretty clear that G-SYNC had significantly more input lag than VSYNC OFF. It was observed that VSYNC OFF at 300fps versus 143fps had fairly insignificant differences in input lag (22ms/26ms at 300fps, versus 24ms/26ms at 143fps). When I began testing G-SYNC, it immediately became apparent that input lag suddenly spiked (40ms/39ms for 300fps cap, 38ms/35ms for 143fps cap). During fps_max=300, G-SYNC ran at only 144 frames per second, since that is the frame rate limit. The behavior felt like VSYNC ON suddenly got turned on.

The good news now comes: As a last-ditch, I lowered fps_max more significantly to 120, and got an immediate, sudden reduction in input lag (27ms/24ms for G-SYNC). I could no longer tell the difference in latency between G-SYNC and VSYNC OFF in Counterstrike: GO! Except there was no tearing, and no stutters anymore, the full benefits of G-SYNC without the lag of VSYNC ON.

This is still low-latency territory

Even when capped out, the total-chain input lag of 40ms is still extremely low for button-to-pixels latency. This includes game engine, drivers, CPU, GPU, cable lag, not just the display itself. Consider this: Some old displays had more input lag than this, in the display alone! (Especially HDTV displays, and some older 60Hz VA monitors).

In an extreme case scenario, photodiode oscilloscope tests show that a blank Direct3D buffer (alternating white/black), shows a 2ms to 4ms latency between Direct3D Present() and the first LCD pixels illuminating at the top edge of the screen. This covers mostly cable transmission latency and pixel transition latency. Currently, all current models of ASUS/BENQ 120Hz and 144Hz monitors are capable of zero-buffered real-time scanout, resulting in sub-frame latencies (including in G-SYNC mode).

The whole article is worth a read in truth and blurbusters have done a lot of investigating. I don my cap to them for their hard work in bringing this info. They end with this news as well, which sounds extremely promising.

This is still low-latency territory

Even when capped out, the total-chain input lag of 40ms is still extremely low for button-to-pixels latency. This includes game engine, drivers, CPU, GPU, cable lag, not just the display itself. Consider this: Some old displays had more input lag than this, in the display alone! (Especially HDTV displays, and some older 60Hz VA monitors).

In an extreme case scenario, photodiode oscilloscope tests show that a blank Direct3D buffer (alternating white/black), shows a 2ms to 4ms latency between Direct3D Present() and the first LCD pixels illuminating at the top edge of the screen. This covers mostly cable transmission latency and pixel transition latency. Currently, all current models of ASUS/BENQ 120Hz and 144Hz monitors are capable of zero-buffered real-time scanout, resulting in sub-frame latencies (including in G-SYNC mode).

Conclusion

As even the input lag in CS:GO was solvable, I found no perceptible input lag disadvantage to G-SYNC relative to VSYNC OFF, even in older source engine games, provided the games were configured correctly (NVIDIA Control Panel configured correctly to use G-SYNC, and game configuration updated correctly). G-SYNC gives the game player a license to use higher graphics settings in the game, while keeping the gameplay smooth.

We are very glad that manufacturers are paying serious attention to strobe backlights now, ever since this has been Blur Busters raison d’être (ever since our domain name used to be www.scanningbacklight.com in 2012, during the Arduino Scanning Backlight Project).

Silent_Scone · 24 Aug 2014 at 10:27

Yep great testing there and addresses most concerns.

pgi947 · 24 Aug 2014 at 11:09

I think they key point is that any change in latency is insignificant, amd say their solution will be around the same figures so everyone wins

I quite like Tom Petersen, he comes across as very genuine and trustworthy - I don't know if this is a good thing in the world of tech hardware though

Gregster · 24 Aug 2014 at 12:15

People seem to be making more of the latency times than what they actually are. They certainly won't bother me.

tommybhoy · 24 Aug 2014 at 12:23

I know, 'latency times being non existent' isn't the same as insignificant, I don't see the need to lie about it, it's a fantastic tech and a win for PC gamers.

1kiwi · 24 Aug 2014 at 12:57

For those of you who can't stand motion blur there is a nice article at bluebusters which explains allot. I don't think I could go back to 60hz now

arc@css · 24 Aug 2014 at 12:59

pgi947 said:
I quite like Tom Petersen

Yeah, he seems to have the most charisma out of any of the speakers I've seen on PC Perspective imo. I quite enjoy the banter between him and Ryan Shrout.

Gregster · 24 Aug 2014 at 13:36

Yer, Tom knows his stuff and does put a bit of PR on it but then again, that is his job. 12 days to go

andybird123 · 24 Aug 2014 at 14:01

Just watched the video, 50 minutes in, gsync's minimum isn't arbitrarily 30fps, it is tuned on a per monitor basis, so if a panel supports 24 or 10 or even 1fps, then that is what the drivers will be tuned to

He also describes what happens when it does drop below, it doesnt revert to vsync as had been suggested, it simply refreshes from the local buffer and is then ready 7ms later (on a 144hz monitor) to get another frame from the gpu, so that is still potentially better than the way vsync would be trying to handle it

shankly1985 · 24 Aug 2014 at 15:28

Gregster said:
So ~2ms when under the monitors refresh rate and ~7ms when over the refresh rate. I can live with that.

http://www.blurbusters.com/gsync/preview2/

Good article there on latency and input lag.

The whole article is worth a read in truth and blurbusters have done a lot of investigating. I don my cap to them for their hard work in bringing this info. They end with this news as well, which sounds extremely promising.

You also forgetting the network latency on source games like csgo, by capping your frame rate you put yourself at a big disadvantage.

Gregster · 24 Aug 2014 at 15:34

shankly1985 said:
You also forgetting the network latency on source games like csgo, by capping your frame rate you put yourself at a big disadvantage.

I don't play CS:GO so I don't care

shankly1985 · 24 Aug 2014 at 15:47

Gregster said:
I don't play CS:GO so I don't care

Battlefield 4 I can also tell difference between vsync on and off and frame rate capped.

So don't just jump to think it's only csgo that is effected by capping a frame rate. Because am sure bf4 is the same. Least I can feel the difference.

Gregster · 24 Aug 2014 at 15:56

shankly1985 said:
Battlefield 4 I can also tell difference between vsync on and off and frame rate capped.

So don't just jump to think it's only csgo that is effected by capping a frame rate. Because am sure bf4 is the same. Least I can feel the difference.

Did you even bother to read what blurbusters wrote? And I guess you have talked yourself out of getting a G-Sync capable monitor

shankly1985 · 24 Aug 2014 at 16:04

Gregster said:
Did you even bother to read what blurbusters wrote? And I guess you have talked yourself out of getting a G-Sync capable monitor

No I'll be getting a FreeSync Monitor, same tech so I have a right to speak about it. Like I said above dont take everything I say as hard facts.

Am here to learn also, so in-case I did miss what BlurBusters said please do pin point me.

Because if Dice handle there Networking anything like Source, where our Latency is matched with the frame rate what I think is true.. then Gsync or freeSync capping the frame rate will give you a disadvantage.

On BF4 have you noticed when the server is having issue your Frame rate also lowers and stutters?

Thats the Latency between you and the server. Now how much of a hit are you doing capping the frame rate? Hit detection seems much better, uncapped, the game feels more 1to1

Gregster · 24 Aug 2014 at 16:07

shankly1985 said:
No I'll be getting a FreeSync Monitor, same tech so I have a right to speak about it. Like I said above dont take everything I say as hard facts.

Enjoy your freesync monitor and what one are you getting? I can't see any

Look at the previous page for blurbusters results

Silent_Scone · 24 Aug 2014 at 16:08

Lol love a bit of Vaporware

jh30uk · 24 Aug 2014 at 16:09

/me looks in NVCP for FreesSync setting (Adaptive Sync).

shankly1985 · 24 Aug 2014 at 16:11

Gregster said:
Enjoy your freesync monitor and what one are you getting? I can't see any

Look at the previous page for blurbusters results

Am in zero rush my friend. Like I said above this just a bonus feature onto the 1440p 144hz monitor I will get. Till I have used it myself on the games i play I'll always have my questions.

I am bring valid points here. Surely am not alone here? A uncapped frame rate is much better then capped? this has been the case since I can remember.

Yeah I read that, but thats not what am talking about. lol There just speaking of Input lag and nothing more.

Gregster · 24 Aug 2014 at 16:32

You are not really asking questions though are you? You are trying to downplay something that a few of us are looking forward to and with zero intention of ever buying a G-Sync monitor. I am sure freesync will be just as good and there are numerous freesync threads where you won't look like you are trolling if you have questions. G-Sync is here and now and people have told you that they don't notice lag but you skip over those and then come out with another daft statement.

I also appreciate that a forum is for discussions and welcome your input but read what people are typing to stop yourself looking silly (no offence).

setter · 24 Aug 2014 at 16:35

shankly1985 said:
On BF4 have you noticed when the server is having issue your Frame rate also lowers and stutters? Thats the Latency between you and the server. Now how much of a hit are you doing capping the frame rate? Hit detection seems much better, uncapped, the game feels more 1to1

Noticed this today in rather dramatic fashion. Seeing fps drops into the low 40's on sli 780's. Running without vsync or fps cap.