I am currently using a triple monitor setup (Asus VE228H) on a single video card (HIS IceQX H695QNT2G2M) with an active adapter. Now when I built this computer 4 months ago, I did enough research that I knew to buy an active adapter, and probably 95% of the time everything works perfectly.
The problem is that every once in a while I will turn my computer on or take it off of standby and the far left monitor (using the adapter) will just simply not turn on. The computer still fully recognizes it (if I open say google chrome which I keep on my left monitor I can click and drag it over to the others) it just acts like it won't come off of standby. Now truthfully this isn't a big deal because every time (so far) that I restart my computer after this happens, everything boots up perfectly. But I will admit to being annoyed that it is happening, and probably even more so because I don't have a clue why.