Installer LiveUSB wont boot with default boot args (Acer C720)

On an Acer C720 Chromebook the Ubuntu installer usb medium will not boot with default args.

The screen goes black with a flashing underline cursor in the top left of the screen, no other output is displayed even with "quiet" and "splash" removed from the boot args.

I can get round this and make the installer boot by adding "mem=1500m" to the boot args and once installed it is no longer a problem and the mem= entry is not required.

The Acer C720 Chromebook is not a standard laptop, it has coreboot instead of a bios and in order to install anything other than chromeos I had to enable SeaBIOS legacy support inside coreboot.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: installation-report (not installed)
ProcVersionSignature: Ubuntu 3.13.0-24.47-generic 3.13.9
Uname: Linux 3.13.0-24-generic i686
ApportVersion: 2.14.1-0ubuntu3
Architecture: i386
CurrentDesktop: Unity
Date: Sun May 11 18:50:43 2014
InstallationDate: Installed on 2014-05-11 (0 days ago)
InstallationMedia: It
SourcePackage: installation-report
UpgradeStatus: No upgrade log present (probably fresh install)