Well the nomodeset option only makes sense with the UMS support and that was
deprecated in January 2013.

So as long as Fedora 20 doesn't compile their kernels with a deprecated feature
they probably won't support nomodeset any more.

Without any logs it would be rather hard to figure out what's going wrong here.

So is there a possibility to attach for example a serial or network console to
grab the last few lines of system log before the machine goes into nirvana?