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Blur Buster's G-SYNC 101 Series Discussion

Talk about NVIDIA G-SYNC, a variable refresh rate (VRR) technology. G-SYNC eliminates stutters, tearing, and reduces input lag.

Re: Blur Buster's G-SYNC 101 Series Discussion

Postby kevindd992002 » 29 Jun 2017, 13:29

Wouldn't GSYNC + VSYNC OFF be the same as GSYNC + VSYNC ON when the fps is limited 3 fps below the refresh rate? VSYNC only triggers at exactly fps=refresh, right? I'm not sure if this is a valid question but I had to throw it out anyway.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby jorimt » 29 Jun 2017, 13:52

@kevindd992002

English doesn't appear to be parini's first language, so I simplified things as much as possible for him, but I'm guessing yours is.

Your assumption is incorrect. I could repeat myself all day on why this is, but the G-SYNC + V-SYNC "Off" vs. G-SYNC + V-SYNC "On" information is readily available in my article. Once you read it in full (or if you have already), I will be happy to offer further clarifications on this, if needed. Just let me know.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby Chief Blur Buster » 29 Jun 2017, 13:53

While 240Hz officially needs DisplayPort at this time -- I've just found out that 240Hz works over overclocked DVI-D on the BenQ/Zowie XL2540:
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby jorimt » 29 Jun 2017, 13:59

Interesting, I think I have a DVI cable laying around somewhere. I could attempt this with my XB252Q and report back.

EDIT: I have a surplus of cables, but apparently they are all HDMI or DisplayPort only. If I order a dirt cheap DVI cable to confirm, any specific resolution or DVI cable-type needed to attempt this?
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby Chief Blur Buster » 29 Jun 2017, 14:08

Properly configured & properly capped 240Hz GSYNC (+ VSYNC ON) produce a nearly lagless equivalent of perfectly-synchronized VSYNC ON.

When we reach 240Hz leagues, the lag is also dramatically reduced even at max cap.

Unlike 60fps VSYNC ON where you can easily get an (measured) additional +33ms of input lag during VSYNC ON 60Hz, you only get an additional +8ms of input lag during non-GSYNC VSYNC ON 240Hz. But if you combine GSYNC + VSYNC ON, and throw in a cap, then you push it it to near +0ms added lag. What's left is simply other overheads (GPU overheads, video cable transmission, LCD GtG pixel response lag, etc), and a very small scanout lag (top-bottom edge of screen has only a 4ms difference = 1/240sec).

The scanout lag becomes the only lag difference between VSYNC OFF versus the "VSYNC ON" equivalent (GSYNC+VSYNC ON). Except that the frame rate is the refresh rate (they're the same thing now) -- if your game is running at 137fps, it looks like perfect 137fps@137Hz VSYNC ON but in a nearly lagless way (Because, you know, 1/240sec scanouts). If framerate fluctuates, the refresh rate is fluctuating perfectly with it.

At this point, you begin to need to run at framerates far above >480fps during VSYNC OFF in order to beat the super-low input lag of 240Hz GSYNC. Our tests showed that 1000fps+ VSYNC OFF still was useful for competitive eSports players (e.g. CS:GO or Quake Live), but it was only a mere few milliseconds more lag (often as little as 2ms!) than beautiful tear-free stutter-free 237fps-capped 240Hz GSYNC.

The fact that refresh cycles and scanouts are 240Hz (4.1ms cycles) instead of 60Hz (16.7ms cycles), makes a massive difference in eliminating the VSYNC ON versus VSYNC OFF lag, and when throwing in a framerate cap, the remaining lag is removed.

In fact, GSYNC+VSYNC-ON at 238fps cap has less input lag than 60Hz 1000fps VSYNC OFF, as seen from our tests.

Image

Image

Back in the 60Hz days, VSYNC ON was extremely laggy.
However, look at how VSYNC OFF lag advantages mostly disappear when you go 240Hz instead of 60Hz.

With 240Hz GSYNC, you have the luxury of nearly lagless "VSYNC ON" look
Not perfect equal to "240Hz 1000fps+ VSYNC OFF", but as seen in the graphs, you're already ~90% closer to VSYNC OFF than VSYNC ON.

But at this stage, lag-wise, you've now already catapulted yourself ahead of most of your competitors even without VSYNC OFF.

You can still run VSYNC OFF whenever you want (especially for your ultra-framerate games like Quake Live), but when you're not competing for a million dollars in eSports, and simply playing your "100fps league" game engines (Battlefield, etc), you probably want to avoid tearing / stutters -- and simply stay in GSYNC unless you're using strobed mode for that particular game (ULMB, etc).

mds83 wrote:For 60fps capped games/emulators, does capping fps to 60 reduce input lag more than 141 on a 144hz monitor?

Emulators are always capped at 60fps, so there's no need to use a superfluous/harmless 141 cap (RTSS/NVInspector) when there's also a 60 cap built into the emulator.

Just simply force the emulator to run in GSYNC mode (that's the hardest part; instructions vary on emulator) then use the emulator's built in 60fps cap, and you'll see over 50%-90% of your emulator lag disappear. Our tests have shown that with ordinary VSYNC ON 60Hz, there can be >33ms of input lag in some emulators. But when you force the emulator to run in GSYNC/FreeSync mode (instead of ordinary VSYNC ON), your lag can fall to one max-Hz refresh cycle despite the 60Hz cap. Plus overheads (GPU, video cable, LCD GtG transitions).

When you run the emulator full screen (GSYNC windowed mode), make sure the monitor OSD confirms the display is running in GSYNC mode at the monitor's maximum refresh rate. The emulator can run at a mathematically perfect framerate (whether it be 53fps or 59.94fps or 60fps or 70fps) with each refresh cycles scanned out really fast (e.g. 1/240sec). It looks like perfect 59.94fps@59.94Hz or perfect 70fps@70Hz, the monitor is automatically refreshing at exactly the same emulator framerate, and the refresh cycles (each) scans-out really fast (1/240sec at 240Hz) for a practically lagless emulator experience.

60fps cap in emulator at 240Hz GSYNC = lowest lag
60fps cap in emulator at 144Hz GSYNC = lower lag
60fps cap in emulator at 60Hz ordinary VSYNC ON = lots of lag

This is because on a GSYNC monitor, properly configured to a high-Hz GSYNC mode, but running at 60fps cap, each refresh cycle will be refreshed-out onto the screen within 1/144sec or 1/240sec, even if there's only 60 refresh cycles per second. It will look like perfectly synchronized 60fps@60Hz VSYNC ON, but with LOT LESS emulator lag. The fluidity of VSYNC ON but without the lag (but miraculously less lag than 60Hz VSYNC OFF!)

Emulators are tricky to configure in GSYNC mode though. Google for instructions. ("MAME GSYNC" or "Retroarch GSYNC" etc). I found instructions on HardForum in less than 60 seconds saying, that for Retroarch, you need at least version 1.3.0, then change retroarch.cfg to a higher rate (e.g. 240Hz), then disable vsync, disable gpu-sync, and audio-sync. Then set frame throttle to 1.0. And viola. Retroarch running in virtually stutterless, virtually lagless GSYNC/FreeSync mode at the emulator's exact preferred frame rate.

That said, I hear audio is more perfect in MAME. You'd want to run the ASIO variant of MAME or GroovyMAME.

Regardless, the important thing is once the emulator is running; (1) make sure it's running smooth at 60fps (looks like 60fps VSYNC ON but without the VSYNC ON lag) and (2) the monitor is reporting GSYNC/FreeSync at the highest refresh rate (144 or 240). Then you generally know it's using the variable refresh rate feature to perfectly sync (in a ultra low lag manner) to the emulator's emulated refresh rate.

mds83 wrote:Also, if I use the GSYNC + ULMB trick, does the GSYNC "Optimal Settings" still apply?

Currently, combining the two is a little bit too bleeding edge to reliably recommend -- we have not yet tested latency of VRR strobing yet.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby parini » 29 Jun 2017, 18:12

How does gsync work with fast sync?
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby jorimt » 29 Jun 2017, 18:36

It does not work well with G-SYNC at all, and shouldn't be used in combo.
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby RealNC » 01 Jul 2017, 02:14

@parini

Your questions have been moved to this thread:

viewtopic.php?f=5&t=3460
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby jorimt » 01 Jul 2017, 09:21

Thanks RealNC, I was going to do just that today; you saved me some trouble ;)

@parini, I will continue our discussion in this thread:
viewtopic.php?f=5&t=3460&start=50
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Re: Blur Buster's G-SYNC 101 Series Discussion

Postby RealNC » 01 Jul 2017, 22:36

Shouldn't this thread be sticky?

No, seriously, it should be sticky and always at the top. However, I can't see an option in the moderation panel.
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