LHC experiments demand on cooling of electronic instrumentation will be ext
remely high. A large number of racks will be located in underground caverns
and counting rooms, where cooling by conventional climatisation would be p
rohibitively expensive. A series of tests on the direct water cooling of VM
Ebus units and of their standard power supplies is reported. A maximum diss
ipation of 60 W for each module and more than 1000 W delivered by the power
supply to the crate have been reached. These values comply with the VMEbus
specifications. (C) 2000 Elsevier Science B.V. All rights reserved.