Dell Precision T3400 (Late 2007) - Manual (Page 260)

260
Adding and Replacing Parts
Replacing the System Board
1 Transfer components from the existing system board to the replacement
system board:
a Remove the memory modules and install them on the replacement
board (see "Memory" on page 157).
CAUTION:
The processor package and heat-sink assembly can get hot. To avoid
burns, ensure that the package and assembly have had sufficient time to cool
before you touch them.
b Remove the heat-sink assembly and processor from the existing
system board and transfer them to the replacement system board (see
"Processor" on page 243).
1 system board 2 back of computer
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2