Résumé : The paper shows that the entry of data centers in the electricity market leads to priceand consumption effects observed in the real world that were quite predictable froma simple conceptual modelling exercise. The size of the associated welfare losses issensitive to specific electricity market characteristics, explaining why they are oftennot comparable across regions or countries. In general, the historical users are likelyto be worse off in the short run. They will recover their losses in the longer run, butonly if the entrant finances its own capacity needs and if the data centers do not haveexcessive bargaining power. The differences in possible outcomes according to contextsuggests that one-size-fits-all policies to manage the shock across countries or regionswill fail to mitigate undesirable effects in some contexts.