Hi,

I am encountering a problem while I am trying to run a paradigm with 144 Hz refresh rate monitor. The task runs without any problem when I set the refresh rate of the displays to 60 Hz. It doesn't show anything on the display when I change the refresh rate to 144 Hz. The ML keeps running through trials and sending the behavioral codes though. But the screen is blank. See some latency tests in the attachment.

The monitors are connected to the NVIDIA GeForce GTX 1660 graphics card using 2 display port cables. The main monitor is connected using a HDMI cable (not used to display stimulus). 3 monitors in total.

Thanks,
Amir

Update:

Jaewon helped to solve the problem. So here is the key point:

"NIMH ML renders the same graphic on both subject and control screens."

In my case, here are the steps that I took. Connected 2 of the monitors using the display port cables to the graphic card and ran them at 144 Hz. One of these is the ML control monitor (monitor 1) and the other one is the subject monitor (monitor 2). The ML control monitor need to be the primary desktop (from the windows display settings). I also needed to connect a 3rd monitor to have a copy of display out (monitor 3). This 3rd monitor (copy monitor) is connected using a hdmi cable and is running at 60 Hz (probably skipping few frames but not important since it is just a control monitor).

My configuration for the displays is: make monitor 1 primary desktop and duplicate desktop on monitors 2 and 3. (1 and 2|3).

This configuration is working for me. There is a minor point though. Monitor 2 is running at 144 Hz (confirmed with a photo diode) and Monitor 3 is running at 60 Hz. And it enables me to see the copy. One could just use DP cable at the 3rd monitor and also run it at 144 Hz.

Thanks Jaewon for your help.

If you interpret my words as an indication that the control screen and the subject screen should have the same refresh rate, it is a misunderstanding. Although NIMH ML renders the same graphic on both screens, only the subject screen is updated in synchrony with the refresh rate. The control screen is not. Therefore, they do not need to have the same refresh rate.

The reason that your current configuration works is because you set a different monitor as the main display, as suggested in the manual. You can still use the 60-Hz monitor as your control screen, after changing the main display. Just drag the main menu window of NIMH ML onto the 60-Hz monitor and run tasks from there.
https://monkeylogic.nimh.nih.gov/docs_MonitorSetup.html

The other half of my words that you did not quote is "... so that Monitor 3 may not be needed", so it was actually a suggestion that you should get rid of the copy monitor. You need to be careful about duplicating the subject screen without a video splitter. The subject screen runs in the so-called exclusive mode and can be created only for one monitor. It has not been tested how the duplication of the subject screen on the video card level will affect the performance. I would carefully verify whether it really runs at 144 Hz and is not interfered by the 60-Hz copy in any way.

I see. Thanks for the clarification. The photodiode comes in handy to verify that refresh rate.