Overclocked monitor lower input lag at below 144 fps VRR?

Talk about overclocking displays at a higher refresh rate. This includes homebrew, 165Hz, QNIX, Catleap, Overlord Tempest, SEIKI displays, certain HDTVs, and other overclockable displays.
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mechag
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Joined: 23 Mar 2020, 04:21

Overclocked monitor lower input lag at below 144 fps VRR?

Post by mechag » 02 Jun 2020, 03:22

Hi. I have 144hz LG 24GL600F-B monitor. The maximum I can overclock to without OSD warning is 153hz.

I was wondering if 153hz top + freesync (48-144Hz range) + 138fps cap in-game is superior to 144hz top + freesync (48-144Hz range) + 138fps cap in-game, or is there no difference?


Also, does overclocking my monitor void warranty ( I live in UK and bought from Ebuyer), and is there a way to prove if a monitor has been overclocked at some point or not?


Thanks in advance.

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Re: Overclocked monitor lower input lag at below 144 fps VRR?

Post by Chief Blur Buster » 02 Jun 2020, 14:31

mechag wrote:
02 Jun 2020, 03:22
I was wondering if 153hz top + freesync (48-144Hz range) + 138fps cap in-game is superior to 144hz top + freesync (48-144Hz range) + 138fps cap in-game, or is there no difference?
Depends.

As a rule of thumb, for refresh rate upgrades, you usually want to increase refresh rates geometrically by at least 1.5x (e.g. jumping 60Hz to 144Hz, or jumping 240Hz to 360Hz) to make the upgrade visually noticeable in reduced motion blur. Even a 2x jump is more advisable (e.g. 144Hz->360Hz upgrade, bypassing 240Hz). Overclockings are less than that, so differences will be extremely subtle.

Image quality point of view
First, compare 144Hz and 153Hz at www.testufo.com/ghosting ... Sometimes ghosting becomes worse when overclocking, because of a GtG-slowdown effect (explained here) ... If 153Hz is superior, then it can be desirable.

Latency point of view
Desktop LCD displays refresh top-to-bottom, as seen in high speed videos. 153Hz will produce a scanout latency of 1/153sec for all frametimes in VRR range, and 144Hz will produce a scanout latency of 1/144sec for all frametimes in VRR range. For screen center, that is 0.5/153sec versus 0.5/144sec. Latency difference is (0.5/144)-(0.5/153) = 204 microseconds difference (0.2ms) in average scanout latency. Be noted, slower GtG also also increase lag from a human reaction time point of view, so if pixel response is significantly slower at overclocked Hz, it can kill the scanout latency advantage.
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mechag
Posts: 11
Joined: 23 Mar 2020, 04:21

Re: Overclocked monitor lower input lag at below 144 fps VRR?

Post by mechag » 03 Jun 2020, 04:07

I realised that the monitor was frameskipping a little bit at 153hz, so in the light of your 3rd point, I am just going to leave it at 144hz top.

Thanks for your response.

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