PowerShell Script to find all systems that have not logged on in the past 90 days. Not users but Workstations or servers.

$domain = "mydomain.com" 
$DaysInactive = 90 
$time = (Get-Date).Adddays(-($DaysInactive))
Get-ADComputer -Filter {LastLogonTimeStamp -lt $time} -Properties LastLogonTimeStamp |
select-object Name,@{Name="Stamp"; Expression={[DateTime]::FromFileTime($_.lastLogonTimestamp)}} | export-csv -path c:\LastLogon_90_Days.csv -notypeinformation