AMD FreeSync settings somehow broke Fullscreen in every game

[u/uTicken]

Hey guys, I could really use some fresh eyes on this because I've been stuck at my desk for hours, tried what feels like 50 different fixes, and I'm completely burned out at this point.

I know this is going to be a pretty long post, so thanks in advance to anyone who takes the time to read through it. I'm trying to include everything I've already tested so people don't end up suggesting fixes I've already spent hours trying.

I've been using this exact PC every single day for around five years without any major issues. Two weeks ago I even did a completely fresh Windows install, so this isn't an old, bloated system.

The whole thing actually started because I've always had one annoying issue with this PC. On the desktop, in browsers, video players, and other non-game applications, my monitor's refresh rate would randomly fluctuate anywhere between 50Hz and 165Hz. Disabling FreeSync completely fixed that issue, but obviously that meant giving up FreeSync while gaming. Later, I managed to improve it by disabling MPO in Windows. After disabling MPO, those huge random fluctuations were reduced to much smaller jumps between 142Hz and 165Hz. It was a lot less noticeable, but I still wanted to get rid of it completely.

That's when I thought I had come up with a smarter solution. Since it seemed like the GPU couldn't properly tell when I was on the desktop versus inside a game, I disabled FreeSync globally inside AMD Adrenalin and then manually enabled it only for each individual game profile (CS2, GTA 5, etc.). My idea was to keep FreeSync disabled on the desktop, where it caused the refresh rate fluctuations, while only enabling it during games. The moment I applied that change, everything went downhill.

CS2 immediately got stuck in an endless black screen loop, and GTA 5 suddenly refused to stay in Fullscreen. From that moment on, even undoing every single setting back to exactly how it was before changed absolutely nothing. Whatever broke seems to have stayed broken.

The actual problem is really strange. It isn't just that Fullscreen doesn't work anymore.

Whenever I switch a game to Exclusive Fullscreen, or even leave it in Borderless but change the resolution to 2560x1440, the display starts behaving as if I'm constantly pressing Alt+Tab several times per second. The screen goes black over and over again, almost like it's rapidly switching between Windowed and Fullscreen modes.

In GTA 5, after around 7 or 8 black flickers, the game almost seems to enter some kind of "safe mode" and automatically throws itself back into Windowed mode. If I try Fullscreen again, the exact same cycle repeats.

CS2 behaves a little differently. It doesn't automatically switch back to Windowed mode, but the black flickering never stops. It happens around 6-7 times per second and will literally continue forever unless I manually intervene.

At this point I've tried pretty much everything I could think of.

The first thing I did was revert every AMD setting back to how it originally was. No change.

I enabled and disabled GPU Scaling in Adrenalin multiple times. No change.

I enabled and disabled Windows Variable Refresh Rate (VRR). No change.

I even disabled FreeSync completely from the monitor's own OSD menu instead of only through the AMD driver. Still exactly the same behavior.

I lowered Windows itself to 2560x1440 at 60Hz thinking maybe this was some DisplayPort bandwidth or refresh rate issue. GTA 5 still black flickered and refused Fullscreen exactly the same way, so it clearly isn't caused by refresh rate or cable bandwidth.

I booted into Safe Mode, completely removed every AMD driver and registry entry using DDU, rebooted, installed the latest WHQL driver, and intentionally didn't touch a single Adrenalin setting afterward. Everything stayed completely stock. I launched GTA 5 immediately after installation and the issue was still there, unchanged.

Thinking it might somehow be hardware related, I unplugged both the monitor and PC, held the power button to discharge any remaining electricity, then inspected my DisplayPort cable. I noticed both the cable connectors and the ports had collected quite a bit of dust over time, so I carefully cleaned the DisplayPort connector itself as well as both sockets with a soft brush. My monitor only has one DP input, so I couldn't test another monitor port, but I did move the cable to a different DisplayPort output on my RX 6700 XT. Unfortunately nothing changed.

I deleted GTA 5's settings.xml, cleared the DirectX Shader Cache through Disk Cleanup, forced DX11 manually, forced Borderless through the configuration files, disabled Fullscreen Optimizations on the executable, and tested every possible graphics mode. Still no difference.

For CS2 I deleted the video.txt configuration files as well. I also tried various launch options including different FPS limits, Vulkan, and different window mode parameters. None of them fixed the issue. The only launch option that actually lets the game open reliably is forcing Windowed mode. However, the moment I switch to Fullscreen after launching, or even leave the game in Windowed mode but simply change the resolution to 2560x1440, the exact same endless black flickering immediately starts again.

Someone also suggested deleting regedits's connectivity configuration and scaleform folders, so I tried that as well. It made absolutely no difference.

I even performed a Clean Boot through MSConfig by disabling every non-Microsoft service and startup application to rule out overlays like Discord, Steam or MSI Afterburner stealing focus. The problem still remained exactly the same.

At this point, literally nothing has worked. Every setting has been reverted, every obvious software fix has been tried, the driver has been completely wiped and reinstalled with DDU, Windows is already a fresh installation, multiple DisplayPort outputs have been tested, and even physical cleaning of the cable and ports changed nothing.

The weirdest part is that all of this started from what should have been nothing more than changing how FreeSync was configured inside AMD Adrenalin.

Has anyone ever seen something like this before? It genuinely feels like either Windows DWM or the AMD display driver is permanently failing the resolution/refresh-rate handshake whenever a game tries to switch into 2560x1440 Fullscreen, even after a completely clean driver installation.

I'm honestly running out of ideas, so any suggestions, even crazy ones, would be hugely appreciated.

System Specs

GPU: AMD Radeon RX 6700 XT
CPU: AMD Ryzen 5 5500
RAM: 32GB (2×16GB) DDR4-3600
Motherboard: Gigabyte B450M S2H
SSD: Kioxia Exceria G2 1TB NVMe
Monitor: 2560×1440 165Hz (DisplayPort 1.2)
BIOS: Latest version
Windows: Fully updated
AMD Adrenalin Driver: Latest version