Did this problem occur immediately after installing the Titan? Did you modify the BIOS to boot with the new card? Consumer PC's require disabling Secure Boot and enabling Legacy Boot or clearing the keys and creating a new key set reflecting the addition of the new graphics card. This is probably not the problem as the system will normally freeze at POST.
Did you uninstall previous graphics card drivers before installing the new graphics card in MB?
Did you install the latest Nvidia graphics drivers after installing the Titan?
This problem could be something else but I would try different Nvidia drivers. Then try going back to the old graphics card to see if this issue goes away.
You could have either an Nvidia driver problem, a conflict with the old graphics drivers if you have not uninstalled them, a Titan hardware problem, or different driver or system file corruption, or hardware problem unrelated to the new graphics card.