Question on VSync with Multiple Monitors

A standard 60Hz Refresh Rate monitor with VSync set to "1/2 Refresh Rate" in Nvidia Inspector and FPS Locked to 30 in FSX are pretty typical settings.

What happens if you have 2 monitors with dissimilar refresh rates though?

I run FSX Full Screen.  I only ALT-ENT and run it in a window if I need to look something up on the net, looks at SkyVector, etc.  Then I go back to Full Screen.

My primary monitor is a 120Hz 1920x1080.

I run a secondary monitor that I don't use to display the actual cockpit or terrain...only instrument windows such as maybe the kneeboard, or maybe move the radio stack over there...thats about it.

The secondary monitor is 60Hz 1920x1200.

I've been using the same settings as many other people:  VSynch set to "1/2 Refresh Rate" in Nvidia Inspector and FPS Locked to 30 in FSX.

Is this incorrect?

Should i be setting my FPS to be locked at 60 instead of 30 in FSX because 60 is half of 120?

I tried setting VSynch in Nvidia Inspector to "1/4 Refresh Rate" once and it just didn't work correctly.  My main monitor kept blinking on and off every few seconds.  It definitely wasn't right.  I assumed that it was because I was "stuck" at the lowest refresh rate of the two monitors.

The whole concept of locking FPS at a given number, manually setting a refresh rate in Nvidia Inspector, etc...all of that is a bit of a foreign concept to me and I don't pretend to understand it all.

Thanks!