r u sure because some people said it needs 20A
For a system using a single GTX 650ti graphics card NVidia specifies a minimum of a 400 Watt or greater system power supply. The power supply should also have a maximum combined +12 Volt continuous current rating of 20 Amps or greater.
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.
Overclocking of the CPU and/or GPU(s) will require an additional increase to the maximum combined +12 Volt continuous current ratings, recommended above, to meet the increase in power required for the overclock. The additional amount required will depend on the magnitude of the overclock being attempted.
The Corsair VS450 (SKU# 75-001835 / CP-9020049), with its maximum combined +12 Volt continuous current rating of 34 Amps and with one (6+2)-pin PCI Express supplementary power connectors, is way more than sufficient to power your system configuration with a single Radeon HD 6670 graphics card.
Whoever told you that it's not enough, they don't know what they're talking about.