Non retina no. Retina is based on ppi, not actual resolution. Retina is apples patented name for such high ppi on screens, like the iPhone, iPad, and new rMBP
does anyone know if its possible to use "retina"-like scaling on an external display.
When I'm connected to the 27/30, things look really small.
Strange how cable documentation often specifies a maximum external resolution of 1920x1080. Glad that's not a hard cap, though.
depends on the cable. DVI limit is 1920x1200. Some older HDMI is 1920x1080 (higher bandwidth can do up to 4k) Dual Link DVI limits each signal to half of your output resolution if your display excedes 1920x1200 (so if you plug a dual link display into a computer using a single link cable you get half res, 1280x800) I don't know the limit of display port...but I know it does 2560x1600, because I am currently using it for that.
So in other words DisplayPort supports a higher limit than DVI, but a resolution that exceeds said limit could still be transmitted as a DVI signal using a DisplayPort-to-DVI adapter?