This is normal.
VRR windowed mode causes microscopic variances in refresh rate with Windows Desktop Manager.
Sometimes it's 143.9Hz. Sometimes it's 144.1Hz. It varies.
It tries to stay fixed but GSYNC-enabled Microsoft Windows is actually continually varying in a microseconds timescale.
It typically doesn't affect anything, unless you're trying to do ultra-precision frame pacing.
RealNC wrote:This is a measurement issue, not a display issue.
Actually, few people know this, but it's actually a normal VRR behavior.
I have the same behaviour when I have GSYNC enabled in windowed mode, when just sitting at the Microsoft Windows Desktop.
The display is simply refreshing on demand by software-triggered refresh cycles via graphics drivers, instead of on its own volition.
One bonus of G-SYNC powered windowed mode is there seems to be
slightly less compositing lag. In exchange for letting your refresh rate be floaty (at the microseconds timescales), you reduce your compositing input lag in WDM a little bit. This is not 100% confirmed, and tests are needed (I'll do some tests soon).
This stops if you turn off G-SYNC
Windowed Mode if this microscopic-variability bothers you. That way, G-SYNC only enables itself in full screen mode. And the display is refreshing itself automatically at virtually nanosecond-exact intervals instead (but that means forcing software to sync to the display -- aka VSYNC ON -- which is harder to be lag-free and stutter-free)
Also, we have our quick refresh rate tester too,
http://www.testufo.com/refreshrate
(Displays 3 digits by default, but can be configured to display up to 8 digits. It usually reaches maximal accuracy within 10-15 minutes)
Note: If it incorrectly says 60 Hz, please see HOWTO: Fix TestUFO Stuck At 60Hz.
Also, most Linux systems will not display this accurately.
Please note, there is a small amount of clock-slewing going on between system clocks, browser clocks, and other clocks based on current clock rate of chip (e.g. Intel SpeedStep can affect this on some chips) so there's some imprecision going on at the 6th or 7th digits. Also, graphics clock may run slightly faster or slower than real world time by a tolerance factor (less than 0.1%). So the slew between computer clock and graphics clock may produce minor inaccuracies, but the ratio should stay fixed pretty well to roughly the 6th digit (after a 10 minute run of this TestUFO Refresh Rate measurement) -- meaning the number eventually will stabilize all the way to approximately the 6th digit -- unless VRR is enabled.
TestUFO Refresh Rate Calculator is one of the Internet's most accurate refresh rate calculators (along with VSYNC Tester) and these two testers are both sensitive enough to pick up when WDM refresh rate is varying -- and it correctly does. Yes, your refresh rate is indeed correctly varying (by design) at Windows Desktop.
Right now, browser microsecond clocks are accurate to 5 microseconds, so this refresh rate calculator is extremely sensitive -- it successfully is capturing your VRR-induced floating refresh rate! Even though one refresh cycle measurement can jitter a lot, by simply timing many refresh cycles over several minutes (and automatically discarding failed/framedropped refresh cycle measurements), TestUFO successfully gains sub-microsecond-accuracy refresh cycle measurement accuracy (assuming the clock slew rate between graphics and computer is sub-microsecond -- this surprisingly is a bigger error factor!)
However, in my experience, this TestUFO refresh rate is ultra-accurate at least to the 3rd digit to realworld time, and to at least 6th digit to graphics clock time (however faster/slower it may be relative to real world time).
So that means if the
2nd decimal digit keeps changing -- then you almost definitely have a floating refresh rate (i.e. software-triggered refresh cycles from WDM -- that's exactly what happens if your monitor OSD says "G-SYNC" while you are at Windows Desktop).
In my experience with TestUFO Refresh Rate after 10 minutes of letting digits settle:
2nd or 3rd digit still keeps changing -- You've got windowed G-SYNC enabled
4th digit still keeps changing -- Clockrate ratio changing (e.g. Intel SpeedStep keeps changing, background web surfing, etc)
5th digit still keeps changing -- Typical slow-performing system.
6th digit still keep changing -- Typical system, idling.
7th digit still keeps changing -- Very fast/accurate/precise system. Congrats if you've locked 6 decmial digits
Varies system-to-system.