10.9.5, late-2012 MBP, HP ZR30w (2560x1600). If I use minidisplayport->dual-link DVI, things basically work, but a few times a day the entire screen suddenly goes black. Not power-saving, just all-pixels-black, for a few seconds. If I use minidisplayport->displayport, it does that a lot more. A *lot* more. Like, it starts out a few times a minute, and after a bit it's pretty much constant; I'll get 1-2 seconds of video, then all-black for 5 seconds, then 1-2 seconds of video. This monitor works perfectly with all my other hardware, but I would prefer to use it on the Mac because it has more real estate than the other monitors. (And actually, at least one of the other monitors does the exact same thing with the Mac.) Reading up on this, apparently this is a thing that sometimes happens with higher-resolution displays, and for which the usual recommendation for Linux and Windows systems is to adjust the refresh rate, because while LCD displays don't "refresh" in the same way that CRTs do, the total display bandwidth used is still affected by resolution*refresh rate. And sometimes if you are close to the edge on what a given piece of hardware can handle, throttling refresh rate down a little bit makes it much more stable. Well, I'd be fine with that, but I can't find anything in OS X that even admits that refresh rates are a thing anymore. I found a shareware utility called SwitchResX which some people reported using to adjust refresh rates to make a monitor more stable, but I can't figure out how to check whether I have in fact adjusted a refresh rate, because there's nothing I can see that will show me a refresh rate. So, various questions: 1. Anyone know of a reason for which displayport would be particularly unusable, while the dual-link DVI connector seems to work fine? 2. Any way to find out what refresh rate currently is? 3. Any idea whether this might be fixed by 10.10? I've been putting off upgrading because I don't like to change things, but I may be about due.