Can't use 1920x1080 Resolution on Xenserver windows 7 guest

XenServer uses Cirrus video driver by default for all new VMs, which provides basic graphics and a maximum desktop resolution of 1024x768.

To get better resolution (up to 2560x1600) and color depth (32bpp), you need to change VM parameters to use Standard VGA driver instead of Cirrus video driver.

1. Shutdown your VM
2. From the command line, find the UUID of your VM:
   • xe vm-list
3. Taking the UUID value, run the following two commands:
   • xe vm-param-set uuid=<UUID> platform:vga=std
   • xe vm-param-set uuid=<UUID> platform:videoram=16

These steps have been tested on XenServer 6.5 and work perfectly!

You can always switch back to using default Cirrus video driver by removing the above defined properties using the following commands:

• xe vm-param-remove uuid=<UUID> param-name=platform param-key=vga
• xe vm-param-remove uuid=<UUID> param-name=platform param-key=videoram

Reference: http://xenserver.org/discuss-virtualization/virtualization-blog/entry/vga-over-cirrus-in-xenserver-6-2.html