Efficient computing the PageRank scores for a large web graph is actually one of the hot issues in Web-IR community. Recent researches propose to accelerate the computation, both in algorithmic and architectural ways. We here focus on a parallel PageRank computational architecture on a cluster of Opteron PCs networked via a Gigabit Ethernet. We propose both an efficient parallel algorithm of the standard PageRank computation, and a simple pairwise communication model needed to synchronize local PageRank scores between processors. Our experimental results conducted on a large web graph, over 1.5 billion links, synthesized from the real set of crawled web pages in the TH domain, are quite promising. The current implementation takes less than 15 seconds for an iteration run.