Four Apple Monitors on a Macbook Pro
EveryMac has some words of warning on trying to run 3 additional displays from a MacBook Pro…


  On a 15-Inch Retina Display MacBook Pro, site sponsor OWC briefly tested three external displays -- two iMacs used as displays at 2560x1440 via Thunderbolt and Thunderbolt/DisplayPort and an LG monitor at 1920x1200 via HDMI -- and shared that "moving images and media didn't create any lag and we were able to play video on all four displays simultaneously."
  
  However, in more detailed evaluation, a helpful EveryMac.com reader reported:
  
  I have a "Mid-2012" Retina Display MacBook Pro with two 27" Thunderbolt Displays daisy chained in clamshell mode. I tried adding a third 1920x1200 Dell monitor via the HDMI port, and it actually does work. But here is the catch: with no external displays, the system fans hover around 2600 RPM. With two 27" Thunderbolt Displays, regardless of what I do, the fans hover around 2800-3200 RPM. The GPU diode temp reads 69°C (156°F). If I force it via a fan control program to run at 2500 RPM, the GPU heats up. I was afraid of damaging my computer so I turned the fans back to auto-mode.
  Now the kicker. I tried with the three monitors and the fans go up to 4800 RPM. That's without doing anything. If I start running a YouTube clip, or do anything remotely CPU or graphics intensive, the fans max out at 5900 RPM (which is the max the machine will do). I exceeded that by having a few videos running at the same time, fired up 3 virtual machines, and had it compile some code. The whole system became choppy and it began stuttering.
  Since then, I've never used three monitors, just the two Apple Thunderbolt Displays. Apple probably doesn't officially recommend using three displays because it gets too hot.
  
  Ultimately, although the Retina Display MacBook Pro models are technically capable of running three external displays as well as the internal one, the above reader is highly likely to be correct. Although Apple does not formally provide a reason for why only two external displays are supported, it is clear that the system can overheat with three connected. Consequently, EveryMac.com does not recommend running more than two external displays on the Retina Display MacBook Pro models.