Thanks for chipping in Leigh :) and noticing by driver blunder, I am pretty sure nv drivers were fubared due to some dependency and i forced my system to use high FC21 drivers.
I have reverted it back and I can successfully boot into 3.17.2 kernel.
[root@syntaxjack ~]# rpm -qa | grep nvidia
akmod-nvidia-331.104-1.fc20.x86_64
xorg-x11-drv-nvidia-331.104-1.fc20.x86_64
kmod-nvidia-3.17.2-200.fc20.x86_64-331.104-1.fc20.x86_64
xorg-x11-drv-nvidia-libs-331.104-1.fc20.x86_64
kmod-nvidia-3.16.7-200.fc20.x86_64-331.104-1.fc20.x86_64
[root@syntaxjack ~]# uname -a
Linux syntaxjack 3.17.2-200.fc20.x86_64 #1 SMP Tue Nov 4 18:04:56 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
[root@syntaxjack ~]#
BUT, if i try to boot 3.17.3 , it absolutely locks up right at start, it wont even show me any LUKS PASSWORD prompt for my encrpted home disk, it is stuck on first three lines, not sure whose issue this is now , nvidia or kernel. atleast i can boot into 3.17.2 now.