Enough power from PSU

[CBJ023]

Hi all, I have a Raidmax 500 watt PSU running a Phenom II x4, a GTX 660, 1 HDD, 1 DVD drive, and two case fans. I'm wondering if adding a case fan, switching from a 80mm to two 120mm cpu fans, and possibly adding two fans on a fan card that mounts below the graphics card will make a big difference power wise and if it'll be close to my 500w limit. Also do USB's use a lot of power? I have 2-3 used right now but soon that'll be 4-6. Couldn't phrase this question well but thank you!

 

[setishock]

CORSAIR Professional Series Gold AX850 (CMPSU-850AX) 850W ATX12V v2.31 / EPS12V v2.92 80 PLUS GOLD Certified Full Modular Active PFC Power Supply - Newegg.com
I use this on my rig.
DZ77GA-70K
i5 3570K
4 120mm case and CPU fans
4 500 gig hard drive
1 optical drive
EVGA GTX650 ti graphics card.
1 external USB fan
Power to spare...

 

[CBJ023]

Well I don't know how much power harddrives take up but forgetting the other three 850 is serious overkill

 

[Celery]

Your 500 watt PSU covers all the voltage. Most of the components uses 12 volts so you need the wattage computed for 12 volt. Look at the label on your PSU and you're see the wattage for 12 volt. Also you need the amperage as well.

Some PSU will give you plenty of amps, some don't so take that in consideration.