Why are refresh rates "off" by a bit?

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LagBuster
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Re: Why are refresh rates "off" by a bit?

Post by LagBuster » 10 Dec 2019, 11:18

RealNC wrote:
10 Dec 2019, 11:08
Never seen anything like this. Only thing I can think of is that something you installed in your machine messes things up. Some driver, some utility, something...
I feel ya. I tried to capture video of what I'm experiencing. My bad because I recorded at 30 fps, and there's a ton of ghosting, but the difference is still visible.

59.981 (stuttery)

phpBB [video]


62.9 (normal)

phpBB [video]


20 (bugged?)

phpBB [video]


Transition from 59.981 (stuttery) to 62.9 (normal) using HRC

phpBB [video]

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Chief Blur Buster
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Re: Why are refresh rates "off" by a bit?

Post by Chief Blur Buster » 10 Dec 2019, 14:10

This definitely is strange/unusual.

I would try:

-- Uninstall your graphics drivers fully
-- Uninstall your monitor fully (right click, remove)
-- Try a different DisplayPort cable on a different DisplayPort on both your monitor and GPU.

Failing that:

-- Test a completely different computer

If this weirdness happens on that different computer, something is bøЯk3d inside the monitor, like a firmware bug, and an RMA is needed.
Head of Blur Busters - BlurBusters.com | TestUFO.com | Follow @BlurBusters on Twitter

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LagBuster
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Re: Why are refresh rates "off" by a bit?

Post by LagBuster » 10 Dec 2019, 14:45

Okay, I now have a rough idea why this happens. The 20 fps thing might just be an unrelated Firefox bug (I'm just guessing) since it happens sometimes but only when I open Firefox, and Windows not recognizing the display sometimes might be "Windows being Windows" or some display controller shenanigans, but the rest is definitely related to GPU clocks/power states, i.e. some timing desync problem between the GPU and the display at a lower power state. The reason I know is that when I have madVR running in the background (with the video paused) the GPU switches to a less aggressive power state and the stuttering is no longer there. With the more aggressive power state, the stuttering is much worse at 59.981, but even at 62.9 it's not completely gone - the only way I can get rid of it is if the GPU enters the less aggressive power state.

Now, my hypothesis is that at lesser resolutions and probably lesser DPI scaling this would not happen, but since I'm at 4K 200% DPI scaling that might have something to do with it (but again, just guessing).
Last edited by LagBuster on 10 Dec 2019, 15:12, edited 1 time in total.

Stitch7
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Joined: 27 Mar 2019, 08:26

Re: Why are refresh rates "off" by a bit?

Post by Stitch7 » 25 Dec 2019, 03:46

clean reinstall of os after complete wipe.

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LagBuster
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Re: Why are refresh rates "off" by a bit?

Post by LagBuster » 25 Dec 2019, 05:40

Stitch7 wrote:
25 Dec 2019, 03:46
clean reinstall of os after complete wipe.
I changed my GPU. ;)

Stitch7
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Joined: 27 Mar 2019, 08:26

Re: Why are refresh rates "off" by a bit?

Post by Stitch7 » 25 Dec 2019, 08:55

Or that :)

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LagBuster
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Re: Why are refresh rates "off" by a bit?

Post by LagBuster » 05 Mar 2020, 07:51

With the new GPU, I was trying to downclock the refresh rate of the monitor below 60 Hz - I set it to 59.95 Hz in CRU but the real refresh rate was 59.99 Hz, so it doesn't seem like I can go below that. I tried 60.003 Hz next to get it as close as possible to real 60 and that made the GPU clocks enter some low power state mode where the idle clocks would be 300-360 MHz (core) and 101.3 MHz (memory) and that caused stutters when scrolling with Firefox. If I overclock the monitor to 62.9 Hz (the max my 4K monitor can handle) the idle GPU clocks are 1245-1530 MHz and the memory frequency stays at its maximum.

EDIT: The low power state mode happens with both 59.95 Hz CRU and 60.003 Hz CRU.

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