External monitor looks dreadful

[NJKA]

Hi all, how to do set up an external monitor to work correctly in Mavericks?

I have a rMBP attached to an 30" Dell monitor @2560x1600 via a display port cable. The Laptop screen looks fine but the Dell screen looks absolutely appalling. Like all the fonts and graphics have been badly scaled. I've checked the resolution is running at its native size, and thats fine.

If I take a screenshot the screenshot looks fine on the laptop but again looks awful on the external monitor, so the OS must be doing some kind of bitmap scaling and the OS is not capable of supporting an external monitor as an independent screen.

Also if I close the laptop lid the result is the same.

Also I cannot now seam to drag a screen across two monitors.
Does OSX not support multiple monitors or is there some way I can fix this.

Thanks

 

[ivan98]

See if this solution is relevant:

http://embdev.net/topic/284710

 

[NJKA]

Thanks allot, that was the cause.

After an hour or so figuring out how to actually use the Terminal I've got it working correctly. Back to work

Thanks again.
Neal