Difference of Lifetime of DMD between 2 situations

Hi.

I want to confirm about following.

Is the lifetime of DMD different between these two situations?

1・[Cock of the each mirror's control]500Hz and ,[ Pattern's changing timing] 68Hz(to use 1.8V ext )

2・[Cock of the each mirror's control]700Hz and ,[ Pattern's changing timing] 68Hz(to use 1.8V ext )

[COMMON]
Num of patterns are 4

And I want to know the detail reason.