The problem of crashing xorg has gone, when i did:
loginctl flush-devices
Now i am able to boot into GUI 
But in this process i lost my second seat 
Other changes i made while analyzing to find the problem:
- /etc/mkinitcpio.conf
- added nouveau to MODULES
- added udev to HOOKS
sudo mkinitcpio -p linux514
cat /etc/mkinitcpio.conf|egrep -v '#'
MODULES=(btrfs nouveau)
BINARIES=()
FILES=()
HOOKS=(base udev systemd autodetect modconf block keyboard sd-vconsole filesystems bootsplash-manjaro)
COMPRESSION="zstd"