For a system using a single Radeon HD 6770 graphics card AMD specifies a minimum of a 450 Watt or greater system power supply. The power supply should also have a maximum combined +12 Volt continuous current rating of 25 Amps or greater and have 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.
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.
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 may 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).
You need to post the brand and model number of your power supply unit if you expect a correct answer.
That PSU is a low quality unit. You can tell right away by the +12V rail which only has 16A. If you do the math (16A x 12V = 192W), that "450W" power supply is only able to supply 192W to the components that need the most power. Compare that to a high quality Corsair VX450 power supply which has 33A on the +12V rail, or 396W.
So, I strongly suggest you upgrade your power supply before upgrading to a video card. Corsair no longer makes the VX450, but you can get a Corsair CX430 for pretty cheap ($25 after MIR, still a good deal without the rebate at $45): http://www.newegg.com/Product/Product.aspx?Item=N82E168...
The CX430 has 32A on the +12V rail, by the way. So even though its listed as only 430W, it's far better than the 450W power supply you currently have.
thnxxxx for the reply!!!
which one is best among these:-
Corsair CMPSU-600CXV2UK 600 Watts PSU
Corsair CMPSU-650TX 650 Watts PSU
Cooler Master GX 650 Watts PSU
Corsair VS650 650 Watt PSU
Corsair Enthusiast Series Modular TX650M - 80 PLUS Bronze Certified 650 Watt PSU
these are available in india!!!
if u want to recommend other PSU's you can recommend other !!
my price range is btw 4000 rs to 6000rs (70$ to 100 $)
nd thnxx fr the reply again!!!