Using a high-refresh monitor beside a 60 Hz screen is a compatibility and workload question, not an automatic error. Many systems can support different refresh rates on separate displays, but behavior depends on the host, driver, connection paths and applications. Evaluate the actual combination instead of relying on a universal claim that mixed rates always cause problems or never matter.
Establish each screen's supported mode
Test the intended resolution and refresh rate for each monitor independently, then check the combined arrangement against the host and dock specifications. A high-refresh screen connected through a limited adapter may never receive its advertised maximum. Another monitor sharing an upstream link can further constrain the available combinations.
Select the correct physical display in the operating system before changing advanced settings. Record resolution, refresh rate, HDR state and relevant color settings. A note containing only high-refresh enabled leaves too much uncertainty if a later test behaves differently. Keep an identifiable known-good mode for recovery.
Bring the pair together and run a representative idle-desktop check, then move to the real workload. Scrolling documents, playing video, joining a call and running a graphics application can exercise different paths. One smooth pointer movement does not establish performance for all tasks, and one problematic program does not prove the entire mixed-refresh concept is unsupported.
Investigate symptoms without changing everything
Describe the problem precisely: uneven animation in one window, video stutter, a dropped mode or a blank display. Keep that symptom separate from a general impression that the screens feel different. A 60 Hz panel will naturally show motion differently from a higher-rate one; that perceptual contrast is not itself evidence of a malfunction.
If a problem is repeatable, change one relevant variable within supported limits. Temporarily using a lower refresh rate or simplifying the connection can help identify a dependency. Record the result and restore the baseline where appropriate. Avoid simultaneous driver, cable and application changes that make a successful test impossible to interpret.
Check current platform and application support information if the issue is specific to a graphics workload. Updates can change behavior, but they should follow an approved recoverable process rather than become the first uncontrolled experiment. A stable configuration that serves the task can be preferable to maximizing a mode with little practical benefit.
Choose the final arrangement according to verified stability and actual priorities. A reference screen may not need the same motion performance as the central task display. Keep the differing rates documented and revisit them when hardware or work changes. Numerical matching is useful only when it solves an observed need, not as an unsupported rule imposed on every two-monitor desk.