Avoiding tearing on multiple monitors running different resolutions by setting custom timing modes

Our application renders using OpenGL into window spanned over entire multi monitor desktop, Windows 7, Aero is disabled (pure dwm), Quadro P1000.

In order to avoid tearing on secondary monitors, we have to set monitors to run custom timing modes that will result in exact same 60.00000000…fps refresh rate which in turn will hold all monitors in sync - forever.

Our problem is that in order to prepare such perfectly synchronized modes for different resolutions we’d have to know what PLL (phase lock loop) formula, coefficients and reference clock frequency is used so no hidden rounding leading to de-synchronization will occur. (such small desync can appear visually after couple of days!)

Can anyone help us please providing PLL details?