Second Monitors and Gaming: What Breaks and How to Fix It
Frame rate drops when a video plays on the second screen, alt-tab problems, mismatched refresh rates and the fixes for each.
The short answer
A second monitor can reduce gaming performance when the two displays run at different refresh rates, because the graphics card cannot idle its memory clocks and must composite both outputs continuously. Setting both displays to the same refresh rate resolves most of it. Using exclusive fullscreen improves performance but worsens alt-tab behaviour, while borderless windowed does the reverse.
Verified and last updated August 12, 2026.
- Time needed
- 13 min
- Difficulty
- Intermediate
- Read time
- 4 min
The second monitor is the best productivity upgrade there is and a persistent low-grade source of gaming problems. Almost all of them come from one cause.
Refresh rate mismatch is the main cause
Two displays at different refresh rates prevent the graphics card from settling into a stable low-power state, and force continuous compositing. Matching them resolves most multi-monitor gaming complaints.
What a second display actually costs
Step 1: Match refresh rates across displays
Set both displays to the same rate 3 minutes
Open display settings and check the refresh rate of each monitor. If your main is 144Hz and your secondary is 60Hz, try setting the main to 120Hz, which divides evenly, or the secondary to the highest rate it supports. Then test in a game and compare.
Divisible rates behave better than arbitrary combinations. 144 and 60 is awkward; 120 and 60 is clean.
If your secondary display cannot match, the alternative is accepting the overhead or disabling the secondary during demanding sessions, which some people script to a hotkey.
Step 2: Choose the right display mode
Exclusive fullscreen: the game takes direct control of the display. Best performance, lowest latency, and the mode that most reduces multi-monitor overhead. The cost is slower alt-tabbing and occasional resolution flickering when you switch.
Borderless windowed: the game renders into a window covering the screen, composited by the operating system. Instant alt-tab, better interaction with a second screen, small performance cost.
Windowed: rarely what you want for full-time play.
There is no universally right answer. For a competitive game you rarely leave, use exclusive fullscreen. For a game you play while doing other things, borderless is worth its small cost.
Step 3: Move background activity off the GPU
Anything hardware-accelerated on the second screen is competing with your game for the same silicon.
The common offenders:
- Video playback, which is decoded on the graphics card
- Browsers with animated content, including many web dashboards
- Discord, which uses hardware acceleration by default
- Streaming software previews, which render continuously
- Animated wallpapers, an underestimated cost
For a game running comfortably, none of this matters. For a game at the edge of acceptable performance, closing the video on the second screen is a real gain.
Discord and browsers both offer a setting to disable hardware acceleration, which moves their work to the processor. That is a useful trade when the graphics card is the bottleneck and a bad one when the processor is.
Alt-tab problems
Games that hang for several seconds on alt-tab, or return with a black screen, are usually in exclusive fullscreen.
Options:
- Switch to borderless windowed for that game
- Disable fullscreen optimisations in the executable's compatibility properties, which sometimes helps and sometimes hurts, so test
- Match refresh rates, since the switch involves a mode change that mismatched displays make slower
Mixed resolutions and scaling
A high-resolution main display with a lower-resolution secondary produces scaling inconsistencies where windows change size when moved between screens.
This is an operating system behaviour rather than a gaming problem, but it affects overlays and windowed games. Setting both displays to the same scaling percentage where possible avoids most of the oddities.
What works
What doesn't
Key takeaways
Frequently asked questions
Why does a second monitor lower my frame rate?
Mainly because of refresh rate mismatch, which prevents the graphics card from settling into a low-power state and forces continuous compositing of both outputs. It also costs a small amount of memory bandwidth. Matching the refresh rates of both displays resolves most of the effect, though a small overhead always remains.
Should I use fullscreen or borderless?
Exclusive fullscreen gives the game direct control of the display, which performs better and has lower latency, at the cost of slower alt-tabbing and occasional resolution flicker when switching. Borderless windowed alt-tabs instantly and works better with second screens, at a small performance cost. Choose per game based on how often you switch.
Does watching a video on the second screen hurt performance?
Yes, because video playback is hardware accelerated on the graphics card, so it competes with the game for the same resources. The effect is small for a single stream and noticeable with several. If a game is already at the edge of acceptable performance, this is a real factor and worth testing.
Can I have different refresh rates without problems?
Modern drivers handle mixed refresh rates far better than they used to, but the mismatch still prevents some low-power states and can cause micro-stuttering. If you have a high refresh main display and a 60Hz secondary, testing both matched and mismatched is worth doing since the difference varies by hardware.
About the author
PC Hardware & Performance Editor
Marcus has been building, breaking and repairing gaming PCs since 2011, first as a weekend favour for friends and then for eight years as a bench technician at an independent repair shop in Portland, where roughly a third of the job was diagnosing machines that "ran fine yesterday".
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