For a
system using a
single GeForce GTX 550 Ti graphics card NVIDIA specifies a minimum of a 400 Watt or greater power supply that has
a maximum combined +12 Volt continuous current rating of 24 Amps or greater and that has at least
one 6-pin PCI Express supplementary power connector.
Total Power Supply Wattage is NOT the crucial factor in power supply selection!!!
Sufficient Total Combined Continuous Power/Current Available on the +12V Rail(s) rated at 45°C - 50°C ambient temperature, is the most critical factor.
You may find power supplies on the market that supply more than enough Wattage to run the system. However, some of them lack Sufficient Amperage capacity on the critical +12 Volt rail, which is necessary to properly power the critical components in the system (i.e. CPU and GPUs). This is the reason why graphics card manufacturers overstate the power supply wattage, usually by at least 50 Watts, in an attempt to take into account some of those power supplies that have the weaker +12 Volt rail(s).
The
Corsair Builder Series CX430 (CP-9020046-NA), with its
maximum combined +12 Volt continuous current rating of 32 Amps and with
one (6+2)-pin PCI Express supplementary power connectors, is
more than sufficient to power your system configuration
with a single GeForce GTX 550 Ti graphics card.
CORSAIR Builder Series CX430 430W ATX12V v2.3 80 PLUS BRONZE Certified Active PFC Power Supply for $44.99 ($24.99 after $20.00 rebate card if purchased between January 4, 2013 and January 10, 2013 at Newegg.com or Newegg.ca.)
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139026
NVIDIA uses an Intel i7-920 system in determining the recommended minimum power supply requirements for their graphics cards.
Get rid of your APEVIA ATX-CB700W.