Could not set the configuration for crtc 64 (15.04)

Based on the specifications for your external screen, I recommend that you change the settings to match it's native resolution. Based on your xrandr output you've got it configured for 1600x1200 @ 60 Hz One of the things the manufacturer suggests doing (in the manual) before contacting the iiyama information line is to check "if the correct native resolution has been selected via 'Display Properties".

To set things up to use the manufacturers recommended resolution you would generate a modeline with cvt. Since this is a TFT display and I can't find any indication to the contrary I'm using a refresh rate of 60 to generate the modeline.

So you'd generate the modeline with:

cvt 1920 1080 60 Which results in output similar to this:

1920x1080 59.96 Hz (CVT 2.07M9) hsync: 67.16 kHz; pclk: 173.00 MHz
Modeline "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync

Then you would apply the modeline with xrandr with:

xrandr --newmode Everything After Modeline from the cvt output including the quotes and then

xrandr --addmode VGA1 1920x1080_60.00

Where VGA1 is the port your display is connected to and the remainder of the line is everything between quotes from the cvt output

Sources:

https://www.manualslib.com/manual/673627/Iiyama-Prolite-E2407hds.html#manual

http://www.kmart.com/asus-n56j-15.6inch-notebook-with-intel-core-i7/p-020V007360940000P

http://www.manualmonitor.com/manuals/iiyama/Iiyama_ProLite_E2407HDS-1.pdf

https://help.ubuntu.com/community/NvidiaResolutionXorgConf

How to set a custom resolution?