The Blue Gene/L supercomputer has broken its own record to achieve more than double the number of calculations it can do a second.
Blue Gene/L is the fastest computer in the world
It reached 280.6 teraflops - that is 280.6 trillion calculations a second.
The IBM machine, at the US Lawrence Livermore National Laboratory, officially became the most powerful computer on the planet in June.
The fastest supercomputers in the world are ranked by experts every six months in the Top 500 list.
Blue Gene's performance, while it has been under construction, has quadrupled in just 12 months.
Each person in the world with a handheld calculator would still take decades to do the same calculations Blue Gene is now able to do every second.
Linton F Brooks from the National Nuclear Security Administration (NNSA) formally unveiled it at the Lawrence Livermore National Laboratory on Friday.
The completed Blue Gene/L joins another supercomputing team-mate, called ASC Purple, to get to work on safeguarding the US's nuclear stockpile.
Purple can do 100 teraflops while it carries out simulations of nuclear weapons performance.
"The unprecedented computing power of these two supercomputers is more critical than ever to meet the time-urgent issues related to maintaining our nation's ageing nuclear stockpile without testing," said Mr Brooks.
"BlueGene/L points the way to the future and the computing power we will need to improve our ability to predict the behaviour of the stockpile as it continues to age."
The machines are part of a decade-long project to develop the fastest computers in the world.
Blue Gene will work on materials ageing calculations, molecular dynamics, material modelling as well as turbulence and instability in hydrodynamics.
Purple will then use that information to run 3D weapons codes needed to simulate nuclear weapons performance quickly.
That analysis had previously taken place in underground nuclear tests.
Supercomputers can help scientists predict climate change
Their massive brains will be able to perform half a petaflop together - that is half a quadrillion (1,000,000,000,000,000) calculations a second.
In a recent demonstration, Blue Gene/L achieved another first by running a materials science application at 101.5 teraflops, sustained over seven hours on the machine's 131,072 processors.
Supercomputers are playing an increasingly crucial role in working out complex problems quickly.
They recently became a major tool in a range of advanced biological applications, from helping to piece together fragmented DNA information to the design of new drug molecules.
Astronomers have also borrowed their brains to re-create how the Universe evolved into the shape it is today.
Their massive simulation and processing power have also been used to improve the accuracy of weather forecasts, help design better cars, and improve disease diagnosis.