Which Core 2 Quad do you have? If you have a slower one like the Q6600, you're probably going to need to overclock in order to get a smooth framerate. If you have a faster one like a Q9350, then you might be okay at stock speeds.
Not sure, but if it's anything for reference, my Core 2 Quad q9400 can't really handle BF4 and bottlenecks my HD 7850 pretty badly (30% usage on Ultra).