Does anyone know what PSU wattage comes with the Inspiron 580 described below? reason I am asking is because on the dell site it says 300W but thats for the I3 CPU . This one below has GPU that comes with it calls  for 400W PSU.

OPERATING SYSTEM	Genuine Windows® 7 Home Premium, 64bit, English	edit
MONITORS	No Monitor	edit
MEMORY	4GB DDR3 SDRAM at 1333MHz- 4 DIMMs	edit
HARD DRIVE	750GB - SATA-II, 3Gb/s, 7,200RPM, 16MB Cache HDD	edit
KEYBOARD	Dell USB Entry Keyboard	edit
MOUSE	Dell USB Optical Mouse	edit
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WARRANTY AND SERVICE	1 Year Basic Service Plan	edit
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OFFICE SOFTWARE	Microsoft® Office Starter 2010	edit
SECURITY SOFTWARE	McAfee SecurityCenter, 30-Day Trial	edit
DATASAFE ONLINE BACKUP	Dell Online Backup 2GB for 1 year	edit
My Accessories
ALSO INCLUDED WITH YOUR SYSTEM
PROCESSOR	Intel® Core™ i5-750 processor(8MB Cache, 2.66GHz)
VIDEO CARD	ATI Radeon HD 5450 1GB DDR3
MODEM	No Modem Option
OPTICAL DRIVE	16X DVD+/-RW Drive
SOUND CARD	Integrated 7.1 Channel Audio
SPEAKERS	No Speaker Option