|There are many things that will determine what is best. The amount of RAM will play a part as well as the type of Nvidia card you have.|
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The important thing to remember is the wattage is only a very rough guide. The amperage on the different voltages is also important. The trend in recent years is for more power to be taken from the 12v rail where previously the 5v rail was more demanding.
However in your case I suspect that the power supply is just dying on its feet and a similar power supply in good working order with suffice.