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Low-Lag Vsync ON - and how it can screw with your head

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#1
A little story from my end, a day in the life of a PC gamer, call it what you will - this just happened.

So, not too long ago, I adopted a brilliant way to avoid tearing + achieve low input lag; taken from
https://www.blurbusters.com/howto-low-lag-vsync-on/

Used the method below: do note the bolded part there...

We found that only one frame-rate capping software, called RTSS (RivaTuner Statistics Server) was able to reduce VSYNC ON lag without adding visible stutters. Other frame rate limiter software (in-game, NVInspector, etc) were not as accurate.
  1. Download and install RTSS.
  2. Go to TestUFO Refresh Rate and measure your exact refresh rate to at least 3 decimal digits.
  3. Subtract 0.01 from this number.
  4. Use that as your RTSS frame rate cap for that specific game.
    For fractional caps, you need to edit two lines in the RTSS config file. Remove the decimal point for the “Limit” line, and configure a divisor in the “LimitDenominator” line. Example of 59.935fps cap:[Framerate]
    Limit=59935
    LimitDenominator=1000
  5. IMPORTANT: Replace “59935” with TestUFO Refresh Rate, subtract 0.01, and remove the decimal point.

Last week, built my new rig and just like many people would, I had to do some simple overclocking, and also touched on overclocking my GPU again (its in a new, much cooler case) because who knows, an extra 13-26mhz may be up for grabs! :p And lo and behold, it actually did clock higher, and remained a lot cooler doing so. Happy Vayra86! Next step: stress/test the OC... Weeee new 3DMark high scores, and my recent Valley and Heaven benchies that I posted here with nice scores.

Next evening, end of a days' work, I fire up the rig for some gaming, I mean, its about time to try those settings for real. I go into RTSS, and change the framerate cap from 0 (unlimited, because stresstests) to 120 like I've done for the past five years. Fire up Overwatch... black screen. RTSS pops up, shows 'D3D11': 0 FPS / 83333ms frametime. I check my GPU clock and load: stuck at 0-1%, 139mhz Core. I try other games, 3DMark, same thing.

I panic. Did I bork my GPU??? Did my CPU OC fall apart? Did my cat piss on something?

To be continued - or rather... WHO KNOWS WHAT HAPPENED? Small spoiler: I did fix it :)
 
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#2
most of the stuff in my life that screws with my head isnt inside my computer , :laugh:
 

FordGT90Concept

"I go fast!1!11!1!"
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#3
I'm guessing you screwed up the Limit/LimitDenominator. To be perfectly honest, that's really slopping coding on the developers' behalf.
 
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#4
10 points to @FordGT90Concept :) ... or one 'Like', at least

LimitDenominator turned 120 into 0.120 FPS...

Had to rewrite the file again and replace it in the RTSS directory to get my 119970 back :toast:
 

FordGT90Concept

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#5
Should be:
Limit=119970
LimitDenominator=1000

Like I said, sloppy coding. It should just ask for 119.970 and do the math it needs to do internally. Breaking it apart is begging for the exact user error you ran into. If there's some reason why they have to be provided separately, it should check the inputs for mistakes and say something about it. Bad program design.
 
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#6
Frame limiting doesn't work. I've tried everything and it just makes image tearing absolutely horrendous on my 144Hz screen no matter what I set it to. 60, 100, 120 or 144Hz, it always starts to tear like insane. Only options that work are Fast V-Sync and Adaptive V-Sync. Low input lag to a point you basically don't feel it with zero tearing.
 
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#7
Frame limiting doesn't work. I've tried everything and it just makes image tearing absolutely horrendous on my 144Hz screen no matter what I set it to. 60, 100, 120 or 144Hz, it always starts to tear like insane. Only options that work are Fast V-Sync and Adaptive V-Sync. Low input lag to a point you basically don't feel it with zero tearing.
Because if you limit the frames they are still not synchronized with the refresh rate in any way.
 
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#8
Frame limiting doesn't work. I've tried everything and it just makes image tearing absolutely horrendous on my 144Hz screen no matter what I set it to. 60, 100, 120 or 144Hz, it always starts to tear like insane. Only options that work are Fast V-Sync and Adaptive V-Sync. Low input lag to a point you basically don't feel it with zero tearing.
That is what this way of implementing Vsync does, in fact. You should really try it. Use the website to measure your real refresh rate, and put it in the global file, run RTSS + Fast Sync.

Frame limiting on its own was never intended to be a tear-free experience. It was meant to reduce GPU temps/loads (so it can boost when FPS dips to maintain FPS cap more readily, as well) in the way Vsync does, but without the input lag penalty.
 
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#9
Because if you limit the frames they are still not synchronized with the refresh rate in any way.
It's not that, it actually makes tearing unbearably awful. Not using V-Sync is just mildly annoying, this made it unplayably annoying. I'm talking about massive tears. It's better to just not use V-Sync then.
 
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#10
It's not that, it actually makes tearing unbearably awful. Not using V-Sync is just mildly annoying, this made it unplayably annoying. I'm talking about massive tears. It's better to just not use V-Sync then.
The old way of fiddling with fps caps was to set it -1 below or above refresh rate, or other values. But yes, the problem never used to go away entirely.
 
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#11
I've tried all of that, nothing worked.