Dell Inc. said Carl Icahn’s proposed alternative to a planned $24.4 billion buyout by Chief Executive Officer Michael Dell is “unrealistic” because of a projected $2.9 billion shortfall.

Based on the estimated gap, the value of Icahn’s proposed $14-a-share offer would be reduced to about $8.15 a share, a special committee for Dell’s board said in a regulatory filing.

The board committee is pointing out shortcomings in Icahn’s offer ahead of a shareholder vote set for next month, seeking to attract backing for the CEO’s plan to take the third-largest personal computer maker private with Silver Lake Management LLC. Icahn and partner Southeastern Asset Management Inc. last week urged the PC maker to make a tender offer for about 1.1 billion shares, his third push to derail the $13.65-a-share buyout proposed by the CEO.

While Icahn and Southeastern’s proposal projects $15.6 billion in liquidity, the company will actually have $12.7 billion, according to the special board committee.

Dell shares were little changed at $13.34 at 9:30 a.m. in New York. They had climbed 32 percent this year through yesterday, compared with a 12 percent gain for the Standard & Poor’s 500 Index.