Most instructions for cooking dried pasta are invariably the same: Drop the noodles into a pot of boiling water, bring it back to a boil, and keep it bubbling vigorously until the pasta is done. We already broke with this conventional wisdom by showing that you can cook pasta in a lot less water than is typically called for, as long as you don’t mind stirring it frequently.
Now we’ve learned that you don’t need to hold your pasta water at a rolling boil either. In fact, you don’t even need to keep the pot on the heat. The pasta will cook just fine if you take the pot off the burner as soon as you add the pasta, cover it immediately, stir once or twice during the first minute, cover again, and leave it to sit for the recommended cooking time. We tested this method with spaghetti, shells, farfalle, and ziti, using the full 4 quarts of water recommended per pound, and we found that the texture was identical to that of pasta we boiled the conventional way.
Source: What Is Low-Temp Pasta?
Don’t forget that you can bring that water to a boil faster if you microwave half of it first. And know why to use cold water, rather than hot.