lol ..maybe your system is way too powerful for that game...lol
to be precise, crashes maybe due to overheating and insufficient power supply.
So pls give me some details about your powersupply unit.
2x 9800 GTx require a ravaging amount of power with max TDP being about 230 watts. If that beast is not being fed by your power supply then it'll make your system pee and not just crash..!!
Haha...details about PSU please..