For those who don't know what Ultra Low Motion Blur (ULMB) is, it is the "official" way that NVIDIA has implemented monitor backlight strobing aka the "light boost hack". Backlight strobing, when implemented correctly, offers great clarity for moving scenes and brings you back to the days of CRT twitchy FPS gaming. More information can be found in this article: http://www.tftcentral.co.uk/articles/motion_blur.htm I have had an Acer XB271HU for a few months now and was using it with a gaming PC I built which supports g-sync and ULMB. Both worked great in Windows, but then I got a cMP 4,1 for "free" (long story but it involves a UPS damage claim), so I decided to try and repurpose it as a gaming machine. As such I popped in an unmodified GTX 980 and went to work. Unfortunately when I set the refresh rate to 120 Hz the menu feature was locked out on the monitor: You could not even select it as an item, it would just get skipped over when going through the menu. I kind of expected g-sync to not work but was disappointed when I saw ULMB didn't since that is more monitor-centric and just requires the monitor backlight to strobe with the fixed refresh rate of the monitor. -------- I finished setting up my bootcamp / Windows 10 install today and played Doom for a few hours. ULMB and G-Sync work in Windows of course and worked well. Done with that, and rebooted back to OS X. Well, now guess what I have: For proof of concept I went to the trusty testufo.com website and made two slow-mo recordings with my iPhone 6S. When ULMB is enabled you can see the screen strobing on/off between monitor refreshes in the video. The scrolling test also shows a clear, easy-to-see figure in the top row like you would normally see when running this test in windows. ULMB ON: https://www.dropbox.com/s/2m0zmaumgd7dxbx/OS X ULMB ON.mov?dl=0 ULMB OFF: https://www.dropbox.com/s/2m0zmaumgd7dxbx/OS X ULMB ON.mov?dl=0 Notice the backlight strobing going on in the first video vs it being non-existent in the second one. Sorry, don't have a pursuit camera to show results any further I figured that most gaming will be done in Windows as it is, but it would be nice for twitchy FPS games like Tower of Guns to be able to do ULMB / backlight strobing without rebooting. At least I get two of the three nice features of this monitor while in OS X (120/144 Hz and ULMB). I still don't understand why it works though. The only thing I can think of is that the g-sync module unlocks the feature when a status flag gets set, which might of happened after I installed in the drivers in Windows and it saw that a g-sync display was connected. I have not tried power cycling the monitor yet, which might erase that flag and not allow me to turn ULMB on until I reboot into Windows again, then go back to OS X. Currently ULMB turns off when I set the display to 144 Hz as it should. I can then go back to 120 Hz and ULMB turns back on. I am also able to turn ULMB off and on now in the menu as well when running at 120 Hz. This probably counts as a niche thing for mac gamers all things considered, but I thought I would share. I'll post any further testing that I do in this thread.