Health Minister Andy Kerr has stepped into the Western Isles Health Board row and installed a new interim chairman.
David Currie resigned after five years as chairman
Mr Kerr, who is also sending a managerial support team to the isles, said he was "fed up" with the board's failure to perform as a corporate body.
The minister's actions followed the resignation of chairman David Currie on Tuesday after five years in the post.
Mr Currie said he had found it increasingly difficult to balance the job with his other commitments.
The board has been dogged by controversies, including accusations of mismanagement and of cutting services.
It faced a vote of "no confidence" by staff back in March.
The executive had previously refrained from stepping into the row and said any dispute was for the chairman and board members to resolve.
However, Mr Kerr said Mr Currie's resignation had opened the way for him to make changes.
They include installing Ronnie Cleland, a non-executive board member of NHS Greater Glasgow and Clyde, as interim chairman.
Also, a support team led by Malcolm Wright, chief executive of NHS Education for Scotland, is to be dispatched.
Mr Kerr said issues affecting the board had not impacted on patient care.
He said: "Western Isles are doing quite well in relation to that, but I have to say the board are not performing the way they should do.
"The board, the non-executives which are the board members and indeed the management team have not been performing as a corporate body as they should have been doing and I am fed up with that."
Alasdair Morrison praised frontline hospital and health staff
He added: "Unless the board members rise to the challenge of working more effectively in the future, I do not rule out further action.
"One of the key roles for the seconded chair will be to consider what further changes are required and rest assured I will make these changes as appropriate."
Mr Currie said delivering health care in the isles would always be a demanding task.
He said: "Nevertheless, during my tenure we have delivered high quality patient services and begun much needed reform.
"However, increasingly I have found it difficult to balance my NHS, personal and business interests and after five years of service as NHS chair I believe the time is right to hand over my responsibilities.
"I believe it is in the interests of the people of the Western Isles, and of this NHS Board, for someone else to pick up the challenge and take it forward from here."
Mr Currie and the board have previously faced calls to stand down from local politicians, including the isles' Labour MSP Alasdair Morrison.
Angus MacNeil, Nationalist MP for the Western Isles, welcomed the minister's intervention.
He added: "But it is a matter of concern that it took the health minister six months to act on the concerns which I and others where bringing to his attention.
"I first asked the executive to become involved at the beginning of February."
Western Isles councillors Angus Graham and Angus McCormack held a Stop The Cuts meeting in March. They were later accused of "scaremongering".
Following Mr Kerr's announcement, Mr McCormack said: "This is a significant step towards resolving the many serious financial and management shortcomings within the board."
In March, the executive rejected a call from nursing unions to intervene after staff gave a vote of "no confidence" in the chief executive, chairman and medical director.
They complained that morale had hit an all time low with Dick Manson, David Currie and John Smith in the top jobs.
Last month, a confidential paper written by the board's new press officer was leaked.
Newspaper columnist John MacLeod's document included criticism of local politicians and said mothers-to-be expected a "pain-free" labour.
Mr MacLeod said the views were his own and not those of the board.
He told BBC Scotland even PR consultant Max Clifford could not improve the board's image if damaging leaks continued.