(Adds details about succession at Relational)
By Supantha Mukherjee, Nadia Damouni and Svea Herbst-Bayliss
July 15 (Reuters) - Hewlett-Packard Co interim Chairman and activist investor Ralph Whitworth will step down on Wednesday to focus on his health, the latest top-level departure from the computer maker as it struggles to return to consistent growth.
Whitworth has stood in as chairman of the world's largest computer maker since Ray Lane relinquished that post in April 2013. He will also take a leave of absence from his hedge fund Relational Investors, with fellow co-founder David Batchelder and other senior managers taking the reins for now.
It was unclear what illness prompted the resignation. The Wall Street Journal reported Whitworth had undergone throat cancer treatment this year. HP declined to comment.
HP's board, which has been on the lookout for a permanent chairman for over a year, will discuss the appointment of a new chair at a meeting this week, HP said on Tuesday.
"While his presence would be a loss, we believe the blueprint for HP has largely been drawn up and believe HP has made meaningful progress in its restructuring and transformation," Wells Fargo analyst Maynard Um wrote.
The Silicon Valley icon is trying to move toward computing equipment and services for enterprises, part of Chief Executive Meg Whitman's effort to revive the PC maker. Wall Street analysts credit Whitman with arresting revenue declines.
But HP has grappled with turbulence in its top ranks. Lane stepped down after HP took a writedown on Autonomy LLC, the software developer it bought for $11 billion and later accused of inflating accounts. Whitworth had led an investigation into Autonomy, whose executives have denied wrongdoing.
Patricia Dunn resigned in 2006 amid criticism over a wiretapping scandal, when she authorized eavesdropping on directors and journalists to plug media leaks.
FORCE FOR CHANGE
Whitworth, 58, has long been a force to be reckoned with in boardrooms. Past successes included convincing ITT Corp to split into three in 2011, and pushing Timken Co to spin off its steel unit. His fund is pushing to break up Manitowoc Co Inc.
Some executives, including eBay Inc CEO John Donahoe, have contrasted his low-key approach with that of Carl Icahn, who often wages public campaigns.
He has served on the boards of companies including Genzyme Corp and Mattel Inc.
While Whitworth's reputation may be outsized, his firm manages roughly $6 billion and is small compared with the likes of PIMCO or BlackRock. Its modest scale makes it vulnerable should investors take their funds elsewhere.
"The perception is that he is the firm and that can make it more difficult," said Geoff Bobroff, an industry consultant who runs Bobroff Associates.
One investor professed support on Tuesday.
"Relational Investors has been a manager for CalSTRS for over a decade and we have great confidence in their team to carry on during Ralph's leave," said Anne Sheehan, director of corporate governance at the pension fund.
(Editing by Edwin Chan and Kirti Pandey; Editing by Richard Chang)