  The Fast Tracker (FTK) is an ATLAS trigger upgrade built for full event,
low-latency, high-rate tracking. The FTK core, made of 9U VME boards, performs
the most demanding computational task. The Associative Memory Board Serial Link
Processor (AMB) and the Auxiliary card (AUX), plugged on the front and back
sides of the same VME slot, constitute the Processing Unit (PU), which finds
tracks using hits from 8 layers of the inner detector. The PU works in pipeline
with the Second Stage Board (SSB), which finds 12-layer tracks by adding extra
hits to the identified tracks. In the designed configuration, 16 PUs and 4 SSBs
are installed in a VME crate. The high power-consumption of the AMB, AUX and
SSB (respectively of about 250 W, 70 W and 160 W per board) required the
development of a custom cooling system. Even though the expected power
consumption for each VME crate of the FTK system is high compared to a common
VME setup, the 8 FTK core crates will use $\approx$ 60 kW, which is just a
fraction of the power and the space needed for a CPU farm performing the same
task. We report on the integration of 32 PUs and 8 SSBs inside the FTK system,
on the infrastructures needed to run and cool them, and on the tests performed
to verify the system processing rate and the temperature stability at a safe
value.
