조립할때 메인보드 뒷면이랑 케이스랑 닫으면 안된다고하는대 영상보면 서로 붙는거아닌가요???나사조립할때??? 그리고 그 절연링??? 볼트 조립할때쓰는사람도있고 안쓰는사람도있던대 상관없는건가요.....