The PrimeNet server is the machine that is the hub of operations for GIMPS.
PrimeNet vs PrimeNet server
While sometimes used synonymously, PrimeNet and the PrimeNet server are two different things. The PrimeNet server is a physical computer with a specific location. PrimeNet is the software that GIMPS uses to co-ordinate work and the associated data.
2008 PrimeNet server crash and V5 upgrade
About the time that M45 and M47 were found, the existing PrimeNet server crashed. The new server was brought online along with a new version of the PrimeNet software (v.5). (The software had been in developement, as had been a new version of Prime95 that was being readied to be rolled out at the same time.) With the arrival of the new server and both software packages, the range of GIMPS exponents being handled by PrimeNet increased from 79.3 million to 999,999,999.
While the crash may have seemed to have come at the worst possible time (the discovery of 2 new primes in quick succession), the new software forced into service has had important benefits. Since one of the 2 new primes was 10 million decimal digits long, it qualified for one of the EFF prizes. This lead to a raised interest in the EFF prize for the first 100 million digit prime. With the expanded range PrimeNet could now host the work being done in the 100 Million Digit Prefactor Project. Also, many that were doing Lone Mersenne Hunters work, could now report directly to PrimeNet server and not manually to George Woltman. Another benefit is the many new reports that can be generated easily. These can be used for a variety of purposes including LMH. Also, the GIMPS statistics have been updated to a newer unit GHz-days and no longer P90 years. Further, the addition of better account controls and more worktypes have been a helpful. Better manual assignment handling has been added too.