Ubuntu doesn't work on some computers, if Ubuntu doesn't work try Fedora.
If Fedora doesn't work try CentOS or RHEL. If those don't work try KNOPPIX, Linux Mint, PCLinuxOS or older versions of Ubuntu and Fedora.
Fedora usually works on computers Ubuntu doesn't work on. Sometimes Ubuntu works with hardware Fedora doesn't work with.
The specs are really important because some hardware is not compatible with Linux, Unix or BSD.