At a time when Atlantic Coast Conference fans and officials are settling in for their annual basketball tournament/party, Clemson University finds itself in the middle of its third major athletic department scandal in a decade.

Three former coaches were indicted this week for illegally dispensing phenylbutazone, an anti-inflammatory agent and painkiller, and steroids, which some athletes use for gaining bulk and weight. The indictments concluded an investigation by state law enforcement officers after Augustinius Jaspers, a world-class distance runner and Clemson student, was found dead in his dormitory room last fall. A nonlethal trace of phenylbutazone was found in his blood.

Six days ago came the resignations of William Atchley, the university president, and Bill McLellan, the school's athletic director who seemed to have more power than the president with the school's 13-member board of trustees.

From interviews this week, it is clear that, although the drug incident played a highly visible part in the scenario leading to the resignations, it didn't cause them.

Rather, the resignations appear to have been the result of a personality clash between two strong-willed individuals, whose actions polarized the board. When Atchley could not get a unanimous vote of confidence, he resigned. The reason for McLellan's resignation -- he asked to be assigned elsewhere in the university -- is less clear. What is clear is that constant infighting between Atchley and McLellan finally came to a head.

The president of Clemson's faculty senate, David Senn, a psychology professor, pleaded for the board to unite behind president Atchley: "The impact would not only be on Clemson, but a message will go to the Division I schools that athletics is strong enough to control the leadership."

Atchley has said that Clemson could become known as "Clemson Athletic University." And, yesterday, after a campus rally in which about 2,000 students marched from the student union to the administration building with petitions supporting him, he said, "It doesn't matter if it's right or wrong. It'll hurt (the university) if it's perceived that way, which it is . . . by the people on the outside."

Atchley, a straight-talking outsider when he arrived at Clemson as president in 1979, tried to reorganize the athletic department in 1982, in the wake of Clemson's second major NCAA probation for improper recruiting and student aid. He took public steps -- later to prove unsuccessful -- to reduce McLellan's power, if not his title. McLellan, the athletic director for 14 years until he took a leave of absence in mid-February, was South Carolina-born, Clemson-educated, a member of the Tigers' 1952 Gator Bowl football team and a successful manager who had been building his political base since joining the athletic department in 1958.

After the football team, which had won the 1981 national championship, was placed on a two-year NCAA probation in 1982, Atchley announced that McLellan would retain his title, but Bobby Robinson would become associate athletic director and would be in charge of football and basketball. A coordinator of athletics also was to have been hired, to report directly to Atchley. "He (Atchley) didn't have the political ability to get that done," said one ACC source.

Walter Cox, the university vice president for student affairs and McLellan's immediate superior, agrees that the dictum by Atchley was "modified." Cox refused to be more specific. But all this had been done in relative obscurity.

The struggle became public early this year, a month or so after Atchley ordered coaches Sam Colson (women's track and cross country) and Stan Narewski (men's track and cross country) suspended and supported a State Law Enforcement Division investigation into charges of illegal dispensation of drugs.

McLellan publicly differed with Atchley, telling reporters he would not have suspended the coaches and would have had matters handled internally. "I begged him to let me do my own investigation," McLellan told the Anderson (S.C.) Independent-Mail.

The faculty senate, in an unprecedented move, issued a vote of no-confidence to McLellan, by a 19-5 margin. Suddenly the board of trustees was divided, or as Senn put it yesterday, "polarized."

Atchley, in his six years at Clemson, also had made enemies in other areas of the university. The anti-Atchley forces formed a coalition that, by the end of last week, brought about Atchley's resignation, effective July 1 -- his response to failure to obtain the unanimous vote of confidence he got 11 months earlier.

"Between now and July 1," Atchley said yesterday, "I'm not going to be a lame duck."

Although no one will say so, it appears that McLellan's decision to step down and seek reassignment -- he will reach early retirement age in two years -- avoided further public damage. McLellan, reached yesterday at his home, declined comment.

Asked how McLellan could have survived a three-year NCAA probation of the basketball team imposed in 1975 and a two-year football probation and helped topple the university president, Cox, his immediate superior, said:

" . . . McLellan is an awfully good manager . . . He's not a p.r. type. He's probably possessive of what he's worked to develop. I'm appreciative of the dollars generated from his programs. The athletic department has supported the university in pretty substantial ways."

The source of the illicit prescription drugs is allegedly in Nashville, where it has been reported that as many as 50 Vanderbilt University football players used steroids. Colson, Sports Illustrated reported, said E.J. (Doc) Kreiss, Vanderbilt's strength coach and a former Clemson athlete, and M. Woody Wilson, a Franklin, Tenn., pharmacist, were the sources for the drugs.

Meanwhile, in Clemson, lawyers for Colson and Narewski said they will plead guilty to misdemeanor charges in Pickens County Circuit Court on Monday. Jack Harkness, a former graduate assistant strength coach, returned home some time ago to Ontario, Canada, and, officials indicate, the U.S.-Canada extradition treaty does not cover such offenses.

Robinson, according to Cox, is the front-runner to become athletic director. The search for a president likely will take a year. It is too early to tell what impact the latest excesses will have on the university, and Atchley, an engineer, is unsure whether he will remain in academe or enter private business.

Atchley has "been a leader nationally (for athletic reforms)," Senn said. "Some of the (Clemson) supporters and trustees resented his participation at a national level."

Atchley says his voice will not disappear, "regardless of what I decide to do. It's a problem all over the United States. That's why we've talked about it so much . . . gone through the pain and heartaches, bringing it into perspective."