I just installed Ubuntu for a tri-boot system. I had Windows 10 x64, then installed Windows 7 x64, then I installed Ubuntu. I've done this in the past successfully, however, this time I had issues installing Ubuntu. I had to hit F5 or F6 when installing and then I had to choose nomodeset (See link below). Now when Linux Boot Screen loads, it loads very slowly (like not enough ram) and from bottom of monitor to the top. This can take up to 30 seconds or so. I never noticed this on other installs, only this one.
My system specs are as follows:
Asus Rampage II Extreme MOBO Intel i7 920 12 GB of RAM Nvidia 970GTX Video card Samsung Evo 840 Pro 1TB Roughly Partitioned+ 500gb windows 10, 450gb Windows 7 and 50GB Ubuntu. give or take a few.