I found a document by Kingston detailing how they work with Server Memory, I believe that this process would, normally, be the same for most known manufacturers. Memory chips, as well as all semiconductor devices, follow a particular reliability/failure pattern that is known as
the Bathtub Curve:
Time is represented on the horizontal axis,
beginning with the factory shipment and continuing
through three distinct time periods:
Early Life Failures: Most failures occur during the early usage
period. However, as time goes on, the number of failures diminishes
quickly. The Early Life Failure period, shown in yellow, is
approximately 3 months.
Useful Life: During this period, failures are extremely rare. The
useful life period is shown in blue and is estimated to be 20+ years.
End-of-Life Failures: Eventually, semiconductor products wear out and
fail. The End-of-Life period is shown in green
Now because Kingston noted that high fail-rates would occur the first three months (after these three months the unit is considered good until it's EOL about 15 - 20 years later). They designed a test using a unit called the KT2400 which brutally tests the server memory modules for 24 hours at 100 degrees celsius at high voltage, by which all cells of every DRAM chip is continuously exercised; this high level of stress testing
has the effect of aging the modules by at least three months (as noted before the critical period where most modules show failures).
The results were:
In March 2004, Kingston began a six-month trial in which 100 percent
of its server memory was tested in the KT2400. Results were closely
monitored to measure the change in failures. In September 2004, after
all the test data was compiled and analyzed, results showed that
failures were reduced by 90 percent. These results exceeded
expectations and represent a significant improvement for a product
line that was already at the top of its class.
So why is burning in memory not useful for server memory? Simply, because it's already done by your manufacturer!