Can't boot LiveUSB: low graphics mode

[ronb2552]

I am trying to install Ubuntu 13.10 alongside Windows 8.1 that was installed with MBR. Created a bootable usb with UNetbootin but when I try to load ubuntu from usb I am stuck at "low graphics mode".

My system:
Gigabye z87-ud3h
i5 4570
AMD radeon 7790

[Bucky Ball]

Welcome. Do you get to a screen with the options 'Try Ubuntu' 'Install Ubuntu' before this screen? If so, hit F6 and try some of the options there then attempt 'Try Ubuntu'.

[ronb2552]

Welcome. Do you get to a screen with the options 'Try Ubuntu' 'Install Ubuntu' before this screen?

Yes I do. I selected 'try Ubuntu'.

[Bucky Ball]

Hit F6 and try some of the options there then attempt 'Try Ubuntu'. 'nomodeset' works for nvidia cards but not sure about AMD.

[ronb2552]

Hit F6 and try some of the options there then attempt 'Try Ubuntu'. 'nomodeset' works for nvidia cards but not sure about AMD.

I think I am not getting the screen you are talking about. I get a black GRUB screen with option "Try ubuntu...", "Install ubuntu"... F6 doesn't do anything.

[Bucky Ball]

Ah. Your drive is set to boot EFI? Could you boot into the BIOS and give it a check? Easier still, when you get to that screen, does it say 'grub-efi' at the top?

[ronb2552]

Ah. Your drive is set to boot EFI? Could you boot into the BIOS and give it a check? Easier still, when you get to that screen, does it say 'grub-efi' at the top?

It didn't say 'grub-efi'. It was something like 'gnu grub 2'. However, I did have 'UEFI and legacy' in bios which I changed to 'Legacy only'. Now instead of grub it boots into some sort of UNetbootin boot with similar options. Selecting 'Try Ubuntu' results in the same 'low graphics mode'.
Thanks for your help.

[Bucky Ball]

If you are booting Windows 8 you MUST leave EFI on, so if you have it off, switch back on, that is not the issue or Win8 will fail to boot. Have you got fastboot and secureboot off in the BIOS?

[ronb2552]

If you are booting Windows 8 you MUST leave EFI on, so if you have it off, switch back on, that is not the issue or Win8 will fail to boot. Have you got fastboot and secureboot off in the BIOS?

Windows 8 boots fine even after setting the boot to 'Legacy only'. As far as I understand my win8 is installed in legacy format( MBR partition table) so that all the UEFI features do not work. However, I did turn off everything I could find that relates to uefi (including fastboot and secureboot) just in case.

[Bucky Ball]

Rules out anything to do with EFi then. When you boot into low-graphics mode is everything working okay, just a stretched screen? If so, when you install you should be able to install drivers for the AMD radeon 7790 fairly easily. They just don't exist on the disk perhaps. This is sometimes the case with proprietary or very new hardware. You need to agree to install the specific driver as part of the third-parties ToS.

There appears to be a driver for it here which you could try installing when you've installed to hard disk:

http://support.amd.com/en-us/downloa...Linux%20x86_64