1984 - finished 13-0 and ranked #1
1981 - got to 6-0 before our first loss (vs. UNLV) and were ranked as high as #8. Finished 11-2 and ranked #13.
1979 - got to 11-0 and ranked #9 before losing to Indiana in the Holiday Bowl. Finished 11-1 and ranked #13.
So in the 7 previous times we started 5-0, we ended the season ranked.