Board Thread:Warhammer 40k General Discussion/@comment-25686730-20141125054012/@comment-25177957-20141127081532

Well since the Emperor of Mankind mentioned that "They shall have such tactics, strategies, and machines that no foe can best them in battle." It is safe to assume that during the implantation process, one of the implants boost an Astartes' intellegence. Although some chapters may have lost this implant or it never worked for them.