I use Argyll 0.70 Beta 8 and I would like to share my experience to save some "problem finding" time to all the Nvidia Quadro owners and Argyll newbies. It looks like dispread has currently problems dealing with the 10 bit RAMDAC found on Nvidia Quadro chips, here is what I get: root@mypc ~ $ dispread -v -yl -k mydisplay.cal mydisplay Number of patches = 836 Setting up the instrument Can't currently use a RAMDAC which doesn't have 256 entriesCan't currently read a RAMDAC which doesn't have 256 entriesPlace instrument on test window. Being an Argyll newbie and knowing few about color calibration and proofing, I ended up having a very wrong ICC profile, because dispread worked on an uncalibrated display and, once created the profile, I loaded it at system startup using dispwin! NB: dispwin fails to load mydisplay.cal exactly as dispread, but has strangely no problems in loading mydisplay.icc. The solution (on Linux, on other systems I don't know) is to force an 8 bit RAMDAC in the "Device" section of xorg.conf using the following directive: Option "Dac8Bit" "True" Restart X server (or simply reboot your system), create your ICC profile, then you can safely remove the previous directive. I suggest the developers should modify dispread code so that it refuses to work if such an error appears, moreover currently the error is only visible if you use the "-v" flag, otherwise you don't get any warning that something very wrong is happening.