Okay, so you have a prebuilt PC, and the motherboard is most likely the P8H61-M Pro. If this board is retail-type, then yes, it should support the i7 3770, but if it is custom manufactured for the pre-built PC, then it might not support the i7 3770. Open up your PC and look at the motherboard, and compare it with online photos of the P8H61M-PRO, see if there are any differences. If no, then you can probably use an i7 3770 with your board.
What CPU do you have right now? One model of the CM6330 already comes with an i7 3770, do you have a different one?