I will presume that you have disabled the other gfx card in the bios, what steps have you done so far ?
To be honest your system should not be crashing, do any other games do similar ?
Have you checked the temperatures of your cpu etc when the crashs occur ? swtor will heat up a system rapidly and if your cooling is not up to par it will cause crashing issues.
It may even be possible that your crash's are related to sound drivers, it is a matter now of process of elimination.
my card runs at about 67-70c at 55 percent fan speed overclocked about 15 percent above stock. This is for all games. my CPU hits about 57c at full load under prime 95 at an overclock to 4.2ghz, 1 hour test. My cpu cooling is a cossair h80, i've mounted a side case fan to help stir the air on the videocard to keep airflow steady and flowing to the top of the case. where it's sucked out by the H80, the case also has top vents. So i dont think heat is an issue.
As for disabling the card in the bios, Yes, i've disabled it, i only get this problem with SWTOR. No other game crashes on me like this. I can play other games for extended amounts of time and not get one crash. So i'm really at a loss to what's going on