  We obtain estimate of the exponential decay rate of semigroup associated with
second order linear differential equation $u"+Du'+Au=0$ in Hilbert space. We
assume that $A$ is a selfadjoint positive definite operator, $D$ is an
accretive sectorial operator and $\Ree D\geq\delta A$, $\delta>0$. We obtain a
location of the spectrum of a pencil associated with linear differential
equation.
