Battery? Are you actually pushing 1000 rms? Wiring? Big 3?
Don't get me wrong, even if you put up all this info, I wouldn't be able to answer, but all these things will probably be factors. Make it easier for the guys that might know.
It depends on a lot of factors. Best bet is to get a voltmeter and turn your stereo off when the voltage dips below 10.8v when no music is playing, your car will barely start but it'll at least start.