My first cabinet was ~2x2x4.. i had 2 muffin fans~55 cfm each~ one for intake and one blowing out... with a 250... DID NOT DO THE JOB... and were kind of loud as F#ck.... So i got 4 inch vortex and built a cool tube... and there were no problems.. Kind of overkill.. it runs about 5 over room temp now... Dont know if that helps any.. but... there it is.
Do not skimp on ventilation!