超人 "superman" is a special kind of 人 "man".
超市 "supermarket" is a special kind of 市 "market".
超導體 "superconductor" is a special kind of 導體 "conductor".
超新星 "supernova" is a special kind of 新星 "nova".
超聲波 "ultrasound" is a special kind of 聲波 "sonic wave".
超媒體 "hypermedia" is a special kind of 媒體 "media".
Just as "超媒體" 是 "超级媒体" 的缩写, so could 超電腦 possibly be a short form for 超级电脑. To me, 超電腦, without a clear context, is ambiguous. 超 could be interpreted as either "super 超级" or "exceeding 超越".