Discover how data from experiments at heavy-ion colliders (the Relativistic Heavy Ion Collider at Brookhaven National Lab and the Large Hadron Collider at CERN) can immediately be compared with first-principles simulations of Quantum Chromodynamics (QCD) to quantitatively probe the fundamental properties of strongly interacting matter, i.e., quarks and gluons at high temperature. The conditions realized in the experiments governed the early evolution of the universe. The necessary high precision for these comparisons is obtained by completely performing our calculations on the GPU. In doing so we simultaneously face a low flop/byte ratio and high-register pressure. See how we deal with these complications and achieve high performance on the Bielefeld GPU cluster with 400 Fermi GPUs.