I dual boot windows 7 64-bit and ubuntu 13.10 64-bit on separate disks, and utilize some overclocking from the BIOS. Windows works fine, however ubuntu can't seem to find any hard drives, except for at stock cpu speeds. While attempting to boot it says Gave up waiting for root device... and ALERT! /dev/sdb7 does not exist. Dropping to shell! A bootable usb stick still works, but gparted doesn't detect any other drives. Have tried: Boot-repair Changing SATA mode in BIOS Newer kernels Older ubuntu versions Not sure it's relevant, but the motherboard is a Gigabyte GA-A75M-UD2H with the newest BIOS version, the CPU an AMD Llano. This is hardly a fatal error, but it's inconvenient to change BIOS settings whenever I want to switch OS, and furthermore I'm quite curious about why it won't work. I'd appreciate any insight into what the actual problem is. So how can I resolve this issue ?