Recently there were some reasons and I've changed PC-GAMESS to FIREFLY 7. But CPU load distribution in parallel mode is the following:
1 thread - 50% CPU load (total 50)
2 threads - 25+25% CPU load (total 50)
3 threads - 25+12+13% CPU load (total 50)
4 threads - 25+8+8+9% CPU load (total 50)
There's a string "PARALLEL VERSION (UNIFIED) RUNNING USING 4 PROCESSES (NODES)" in the resulting file. The name of .dll for parallel calculations is "mpibind.nt-mpich-smp.dll".
Who knows what the problem is?