Do you have same blackouts in the sim (or any other application?) or just in that shoot-em up game?
Maybe try to update the graphics driver..... and do any windows updates to ensure your system is up to speed. After updating all, shutdown PC.
Unplug the monitor and let it sit for a few minutes. Re-seat the monitor cables on the monitor port as well as on the GPU port. (or if you have another cable, try it - just to make sure. (Rule any/every problem out!).
Do a fresh startup and test it in that same game scenario (without anything else running) (memory at MAX).
If it is still blacking out in that application, try a similar application: graphics heavy like the sim. Any blackouts in the sim?
If blackouts in any application (GPU under load heavy), then suspect it could be either your GPU or monitor telling you that it might be getting tired! (But if only blacking out in that game but OK in everything else, then suspect it's the config of that shooter game- might be using too much memory for your GPU to handle or something else might be running or interfering). Always have to try to determine/isolate the problem as to why something is happening.