I'm not wrong about the PSU, my GFX uses 300 watts or there about's, its overclocked from 880MHz core to 930MHz and could go higher than that if I wish. My cpu uses around 150W, then there is the motherboard, the drives, the 7 case fans etc. You really think a 330W psu could handle that?
As for my fps I get an average of 80 never goes below 70 except in the fleet and WZ's
EDIT: Yes alienware are wrong as I built my rig (see sig) which is much higher spec than yours and more than likely a lot cheaper.