Could not switch the monitor configuration/could not set the configuration for CRTC 64

[Alex]

I got 4 monitors to work prefectly fine all in mirrror mode, but if i try to switch to extended desktop i get "The selected configuration for displays could not be applied/could not set the configuration for CRTC 64" error, then either none or only one montitor of GPU2 works but its glitchy and not smooth like blinking cursor etc... I'm on ubuntu 14.04

$ uname -r
3.13.0-24-generic

$ X -version
X.Org X Server 1.15.1
Release Date: 2014-04-13
X Protocol Version 11, Revision 0
Build Operating System: Linux 3.2.0-37-generic x86_64 Ubuntu
Current Operating System: Linux Vini 3.13.0-24-generic #47-Ubuntu SMP Fri May 2 23:30:00 UTC 2014 x86_64
Kernel command line: BOOT_IMAGE=/vmlinuz-3.13.0-24-generic root=/dev/mapper/ubuntu--vg-root ro quiet splash nomdmonddf nomdmonisw vt.handoff=7
Build Date: 16 April 2014  01:36:29PM
xorg-server 2:1.15.1-0ubuntu2 (For technical support please see http://www.ubuntu.com/support) 
Current version of pixman: 0.30.2
	Before reporting problems, check http://wiki.x.org
	to make sure that you have the latest version.

$ sudo lspci -nn | grep VGA
01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] RV630 XT [Radeon HD 2600 XT] [1002:9588]
04:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] RV630 XT [Radeon HD 2600 XT] [1002:9588]

$ sudo lshw -c video
  *-display               
       description: VGA compatible controller
       product: RV630 XT [Radeon HD 2600 XT]
       vendor: Advanced Micro Devices, Inc. [AMD/ATI]
       physical id: 0
       bus info: pci at 0000:01:00.0
       version: 00
       width: 64 bits
       clock: 33MHz
       capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
       configuration: driver=radeon latency=0
       resources: irq:46 memory:c0000000-cfffffff memory:fe6e0000-fe6effff ioport:a000(size=256) memory:fe6c0000-fe6dffff
  *-display
       description: VGA compatible controller
       product: RV630 XT [Radeon HD 2600 XT]
       vendor: Advanced Micro Devices, Inc. [AMD/ATI]
       physical id: 0
       bus info: pci at 0000:04:00.0
       version: 00
       width: 64 bits
       clock: 33MHz
       capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
       configuration: driver=radeon latency=0
       resources: irq:47 memory:d0000000-dfffffff memory:fe9e0000-fe9effff ioport:d000(size=256) memory:fe9c0000-fe9dffff

$ sudo xrandr
Screen 0: minimum 320 x 200, current 7680 x 1200, maximum 8192 x 8192
DVI-0 connected primary 1920x1200+0+0 (normal left inverted right x axis y axis) 519mm x 324mm
   1920x1200      60.0*+
   1600x1200      60.0  
...snip resolutions...
DIN disconnected (normal left inverted right x axis y axis)
DVI-1 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 531mm x 299mm
   1920x1080      60.0*+   50.0     59.9  
   1920x1080i     60.1     50.0     60.0  
...snip resolutions...
DVI-1-2 connected 1920x1080+3840+0 527mm x 296mm
   1920x1080      60.0*+   50.0     59.9     30.0     30.0  
   1920x1080i     60.1     50.0     60.0  
...snip resolutions...
DIN-1-1 disconnected
DVI-1-3 connected 1920x1080+5760+0 527mm x 296mm
   1920x1080      60.0*+   50.0     59.9     30.0     30.0  
   1920x1080i     60.1     50.0     60.0  
...snip resolutions...
  1920x1080 (0x45)  148.5MHz
        h: width  1920 start 2008 end 2052 total 2200 skew    0 clock   67.5KHz
        v: height 1080 start 1084 end 1089 total 1125           clock   60.0Hz
...snip resolutions...