You're eyeing a 240 Hz monitor, but will your build ever produce 240 frames per second? Refresh rate (Hz) is the maximum frames a panel can show per second — if your in-game FPS lands at 120, you're paying for a ceiling you never reach. Matching the panel to realistic output is how you avoid an expensive paper-spec win.
The Monitor Hz → FPS Reference makes the relationship concrete. It shows what FPS you need to "satisfy" a given refresh rate and whether your target hardware is in the ballpark at your resolution and settings. With FreeSync or G-Sync, matching FPS to Hz (or just below) gives smooth motion; a huge gap just means you overpaid for the panel.
Resolution and detail settings move the FPS number more than anything else, so test the target, not the dream. A 144 Hz panel is a sweet spot for many builds that can't sustain 240, and the reference helps you pick the tier your rig can actually feed instead of chasing a number on the box.
One more link in the chain: sustained FPS depends on thermals. The Thermal Headroom tool checks your CPU cooler rating against its TDP — if the cooler is at or below TDP, the chip throttles under load and your real-world FPS drops below the estimate. Cool it properly and the frames you planned for actually show up. Check the Hz-to-FPS fit, then confirm the cooling headroom.