rMBP early 2013 15'' fan noise with 4K display? I own a MacBook Pro with Retina display early 2013 with Intel HD4000 + GT 650M 1 GB.
I'm looking for a high pixel display, and narrowed it down to two options:
21:9 34″ LG 3440x1440 or 28″ 4K display.

I'm currently using my MacBook Pro with 24″ 1920x1200 as a secondary display for work with Ps, Ai and Ae, and Mac is beautifully quiet even with 8 virtual desktops, Ps, Ai, Safari with ~30 tabs, which I love most about Macs—I start to hear the fans when using Ae and rendering/saving to RAM which of course is understandable.

Is my MacBook going to be quiet with 4K display with at least browsing internet through Safari? It's ok to hear fans when I do some work, but I would hate it if the idle Mac connected to the external display would buzz like a vacuum cleaner!
I have the same machine and the fans do run when trying to display 4k... it's a pain but it appears that whenever the dedicated graphics card comes online it immediately tries to cool the machine... I'm also running OSX Yosemite if that helps.