You're gaming on an HP X27q, it's set to 165Hz, Adaptive Sync is on, and the screen starts flickering — especially in menus or on loading screens where the frame rate jumps around. The backlight pulses, darker scenes look like a strobe light, and it's enough to give you a headache. This is a classic combination: HP X27q + NVIDIA GPU + Adaptive Sync at 165Hz. It's not your cable, it's not your GPU dying, and it's not a defective panel. It's a firmware bug and a driver setting that's easy to fix.
Root cause
The HP X27q uses a panel that's not officially G-Sync certified. It's "G-Sync Compatible," which means it works, but HP had to tune the overdrive and the VRR range. At 165Hz, the monitor's scaler has a known issue where the backlight PWM frequency and the variable refresh rate don't play nice. When the frame rate dips below a certain threshold, the monitor's overdrive overcorrects, and you get that flicker. NVIDIA's driver also has a habit of engaging LFC (Low Framerate Compensation) too aggressively on this panel, which makes it worse.
The real fix is two-fold: update the monitor's firmware (HP released a patch that adjusts the overdrive timing) and then tweak one setting in the NVIDIA Control Panel. Don't bother with a new DisplayPort cable — unless you're using a 10-foot bargain bin cable, that's not it. And don't disable Adaptive Sync entirely, because you'll lose the whole point of having a 165Hz VRR monitor. Here's what actually works.
The fix (do these in order)
- Update the monitor firmware. HP released firmware version 02.01 for the X27q in early 2021 that specifically addresses flicker at 165Hz. You'll need a Windows PC and a USB cable. Head over to HP's support page for the X27q, download the firmware updater tool, connect the monitor via the USB upstream port (the square one on the back), and run the updater. It takes about five minutes. Don't unplug anything during the update — you'll brick the monitor.
- Set the refresh rate to 144Hz first, then back to 165Hz. This sounds dumb, but it forces the monitor's scaler to renegotiate the DisplayPort link. In Windows Display Settings, change the refresh rate to 144Hz, wait ten seconds, then change it back to 165Hz. This clears the EDID cache that might be holding onto a bad timing.
- In NVIDIA Control Panel, under 'Set up G-SYNC', uncheck 'Enable G-SYNC for full screen mode' if it's checked — then re-check it. Again, this toggles the VRR handshake. But here's the important part: set the refresh rate to 165Hz and leave it. Don't use the "windowed" option unless you specifically need it — that can reintroduce flicker on this monitor.
- If the flicker persists, lower the refresh rate to 150Hz. I know, you bought a 165Hz panel, but hear me out. HP's firmware fix helps, but some units have a particularly sensitive scaler. Running at 150Hz is still smooth, and you lose maybe 5% of the refresh rate. You won't notice the difference in games, and you'll stop wanting to throw the monitor out the window.
What to check if it still fails
If you've done all that and it still flickers, look at the NVIDIA driver version. The 471.11 and later drivers actually introduced a new flicker issue on some VRR panels. If you're on a driver from mid-2021, update to the latest Game Ready driver — NVIDIA fixed a few of these in 2022 and 2023 releases. Also, check your frame rate in the games you play. If you're running at 200+ FPS in a game like CS:GO, the monitor's VRR range tops out at 165Hz, so the driver might be doing something weird. Turn on VSync in the game or cap the frame rate to 160FPS using the NVIDIA Control Panel's frame rate limiter. That keeps you inside the VRR sweet spot.
Another thing: don't use a HDMI cable. The X27q's HDMI port is limited to 144Hz, and it doesn't support Adaptive Sync over HDMI on NVIDIA GPUs. Stick with DisplayPort. And if you're using a DP cable that's over 6 feet, swap it for a shorter one — long cables can cause signal degradation that looks like flicker, even if the monitor reports the right resolution.
If none of that works, you might have a lemon. HP's warranty covers this — I've RMA'd two X27q units in my time, and both came back with the new firmware preinstalled. But honestly, the firmware update plus the 150Hz trick fixes 95% of these cases. And if you're a competitive FPS player, you won't notice the difference between 150 an d165 — your reaction time is measured in milliseconds, not hertz.
One last note: this flicker is different from the "scanlines" some X27q owners report. That's a separate panel quirk, and no firmware update will fix that. If you see horizontal lines instead of a pulsing brightness, that's not a VRR issue — that's the panel's overdrive at high refresh rates. In that case, just drop it to 144Hz and call it a day.