Screen occasionally flashes black
No one can tell you with 100% certainty, but my top two guesses are the video card driver and the power supply. Since you're using such a new OS it would not surprise me at all to hear of driver bugs. Check the Nvidia forums for other users with similar problems, and also see if there is a newer beta driver available that you can test with.
If the issue lies with the power supply, either yours is not up to the task, or it's failing/faulty. What power supply are you using? I suggest buying or borrowing a quality power supply rated above what you need and testing to see if you still encounter this problem.
Other possibilities are: Hardware problem with the video card, or bios bug in the video card. If you can easily exchange the video card it would be worth a try. If not, updating its bios is also worth a try, though that is really a last resort long shot.
A friend of mine had the same problem on his new computer. It ran perfectly using OpenSuSE and the nVidia proprietary Xorg driver, but did not work in either 7 or XP (he almost immediately downgraded to XP due to other software constraints - that was back in early 2012 and some all-important software was not (yet?) 7-compliant).
However, the only way to get the monitor behave with Windows was to splice two cables and go analog (and "fuzzy"), otherwise the monitor would "click" every minute or so (apparently depending on temperature), temporarily blanking the screen. We both immediately recognized this as the "changing resolution, please wait..." behaviour. No driver update solved the problem.
After an evening of head-scratching, rebooting and taking notes, we finally noticed that the monitor resolution was not reported the same everywhere; Linux consistently insisted that it was slightly less than 72 Hz (I think it was 71.98), while Windows diagnostics said 72 Hz. The other resolutions were slightly off as well. We reasoned that if some widget in the system was running at 71.98 and another was treating it as 72, maybe one of them would notice the discrepancy once it had became large enough, and that might well have happened every minute. The fact that it happened more often when running hot could be attributed to thermal drift. And then some emergency resync would take place, and that could have explained the blanking.
We started voodooing with nTune utility, and soon started trying "registry frequency" hacks. We also fiddled with the NVTweak utility.
In the end we found a utility by CleverTec, along with instructions on how to tweak the registry and cram the calculated values down into the Windows driver's throat.
So the good news is that the problem is software, is in the driver, and can be fixed.
The bad news is that I couldn't for the life of me come out with a precise HOWTO, since in the end we were pretty much moving at random, after having arrived at our wits' ends. I can't even guarantee that it was DTD alone that fixed things (I am quite confident, but not completely): maybe it only worked because of the previous work on nTune/NVTweak.
Also, be aware that tweaking frequencies can wreck both card and monitor. It never happened to me using X (where there's the same warning), and when I botch things usually the monitor clicks and displays "Frequency out of range", nothing more. But be careful all the same.