Computers requiring 1 to 400 W of refrigeration at 78 K can use standard commercial Gifford-McMahon-type refrigerators similar to those being produced for cryopumps. The computer elements would be immersed in a liquid-nitrogen bath in which heat transfer between the circuit elements and the bath can carry away 5 W/cm2. The elements would operate very near the 78-K bath temperature. Vapors from the boiling liquid would be recondensed on the cold refrigerator, located above the bath, and would fall back into the bath. For smaller computers, simple Joule-Thomson refrigerators could be developed. For larger refrigerators, reverse Brayton cycle refrigerators could be developed.