The coup de grace to Dennis Hayes’ attempts to rebuild his failed eponymous modem manufacturer has surely been delivered by latest rival suitor, San Jose’s PC and Mac graphics supplier Diamond Multimedia Systems Inc. Hayes, in Chapter 11 protection these past 18 months, had at first seemed destined to become part of US Robotics, who unexpectedly withdrew from bidding last week. Suitors then narrowed to Hayes founder and CEO Dennis Hayes and Diamond. Bid and counter bid escalated until Diamond attempted to wrest the company’s remains from Hayes with a final offer of $128m last week ($103m stock, $25m in cash). But only a few hours after the offer was lodged with the Atlanta Bankruptcy Court, Diamond management and advisors announced they had raised the offer to $140m ($112.7m stock, $27.3m in cash) to put all questions to rest.