Best FPS=(Hertz*2)+1?

[HM204DTA]

For example, if you have a 144Hz screen the optimal FPS (using the common formula for Source) would be

(Hertz*2)+1
(144*2)+1
289=(144*2)+1
289fps ~fps_max 300

[Chief Blur Buster]

It depends on your goals:

-- Latency
-- Microstutter
-- GSYNC versus VSYNC OFF
-- Low-Lag VSYNC ON
-- Synchronized versus unsynchronized.
(i.e. RTSS S-Sync is kind of a "synchronized" VSYNC OFF).

There is a beat-frequency behaviour and slow-rolling tearline behaviour when you're too exact (but still unsynchronized) with VSYNC OFF

There are some situations where you want an ultra-tiny differential and some situations where you want a larger differential.

GSYNC / FreeSync / VRR often works best with a 3fps below Hz. VSYNC OFF often works best with ultrahigh frame rates. Double framerate as Hz with a small differential to avoid beat-frequency side effects, is a common tweak with CS:GO because CS:GO can often easily run at twice Hz. But if you are using a lower Hz (e.g. 60 Hz or 75 Hz) you can even use 3x differential or 4x differential and get even better results too. And if you're at 240Hz already, you may not be able to use 2x differential. Basically you want to find your valley framerate (e.g. dips to say ~240fps) and use that as your multiplier. So if you always run at >240fps on a 60Hz monitor, then you can cap at 4x differential with a small offset (e.g. 1fps or 2fps higher or lower) to help randomize the tearline positions (instead of a slow-rolling tearline).

There are many different goals why a bigger or smaller cap differential is needed.