ACM SC: International Conference for High Performance Computing, Networking,
Storage and Analysis
ACM International Conference of Supercomputing (ICS)
IEEE International Parallel & Distributed Processing (IPDPS)
ACM SIGPLAN Symposium on Princeples and Practice of Parallel Programming 
(PPoPP)
Some special topics may also be in ACM ASPLOS, ACM PLDI, ACM ISCA