When one monitor is blank, begin by identifying which part of the signal path has stopped working. Power, input selection, the cable, an adapter, the host output and the operating-system layout can all produce a dark screen for different reasons. Changing graphics drivers immediately may add complexity before the simpler possibilities have been separated.
Distinguish a dark panel from missing video
Check the monitor's documented power indication and whether its on-screen menu appears. A visible menu can show that the panel is powered even if no source image arrives. A selected input that does not match the connected cable may produce a no-signal message. Follow the exact monitor's controls rather than assuming every model switches automatically.
Inspect the physical route without forcing connectors or opening equipment. Confirm the cable reaches the intended host output and monitor input, and check any required adapter power. A directional converter used backward is a different problem from an unselected input. Keep the route explicit so each observation relates to one component.
Check whether the operating system detects the monitor and whether it is enabled in the desired display mode. A detected but disabled screen may remain blank even when the cable is sound. A system showing only one stream through a splitter cannot be configured into two independent workspaces simply by selecting extend repeatedly.
Use controlled substitutions
Where safe and supported, test one display through a known-good direct route at a documented mode. Change one variable at a time: cable, host port or screen. Record which combinations work. Swapping several items simultaneously can produce a picture without revealing the actual fault, leaving the next recurrence just as difficult to explain.
If each monitor works alone but the pair fails, inspect the host's simultaneous-display and combined-mode limits. The evidence may point to a shared capacity restriction rather than two independent hardware failures. A lower supported mode can help test the hypothesis, but it should not be presented as proof until the specification and observed behavior agree.
Only after the basic path is understood should software changes be considered through an approved recoverable process. Check current support information and retain the working driver or settings baseline where appropriate. Avoid installing unrelated packages simply because the screen remains dark; the required software depends on the actual display technology.
Write down the observed symptom and successful test route before returning cables to their final positions. A useful conclusion is specific, such as one cable fails on a verified working route or the dock supports only a lower combined mode. That evidence supports an appropriate repair or configuration decision instead of treating every blank display as the same generic driver problem.