  A number of scientific numerical codes can currently exploit GPUs with
remarkable performance. In astrophysics, Enzo and Ramses are prime examples of
such applications. The two codes have been ported to GPUs adopting different
strategies and programming models, Enzo adopting CUDA and Ramses using OpenACC.
We describe here the different solutions used for the GPU implementation of
both cases. Performance benchmarks will be presented for Ramses. The results of
the usage of the more mature GPU version of Enzo, adopted for a scientific
project within the CHRONOS programme, will be summarised.
