Try also installing the Unofficial Skyrim, Dawnguard, Hearthfire, Dragonborn and High Resolution DLC patches. They fix a lot of bugs within the game and the DLCs, preventing some of the possible crash reasons.
If it still crashes, skip the opening sequence by using the Alternate Start - Live Another Life mod.
Live Another Life provides an alternative means to start the game for those who do not wish to go through the lengthy intro sequence at Helgen. You will be given the opportunity to choose your race and then choose a new life for your character to lead. A wide variety of choices will be available.
Another mod that you might want to try is: SSME - Skyrim Startup Memory Editor.
This… patch will allow Skyrim to use… available space right from the start to fix ILS (infinite loading screen) without side effects and other memory related CTD (crashes to desktop) or freezes.
When tesv.exe is started it allocates two 256MB blocks of memory. When the first block gets full, the engine will allocate more blocks. This can cause the known troubles. Thankfully, by telling the engine to request a bigger block from the start it magically makes use of it without any further ado. This isn't the case with the second block. Thankfully again, the second block does not fill up as quickly and once it is full the engine does not trip over itself when allocating more blocks.
To make the engine allocate a larger block of memory it needs to be patched.
Also, use BOSS to optimize the load order of the mods and DLCs.
BOSS is designed to assist mod users in avoiding detrimental conflicts, by setting the correct load order for the plugins they have installed.
BOSS also provides thousands of plugin-specific messages, including usage notes, Bash Tag suggestions, requirements, incompatibilities, bug warnings and installation mistake notifications.
If it still crashes, I'd recommend "cleaning" the DLCs.