basic remote parallel SystemInfo demo script

#requires -RunAsAdministrator

# fake reading in a text file
#    in real life, use Get-Content
$ComputerList = @'
LocalHost
10.0.0.1
127.0.0.1
BetterNotBeThere
'@ -split [environment]::NewLine

$TimeStamp = (Get-Date).ToString('yyyy-MM-dd_-_HH-mm-ss')
$ReportPath = $env:TEMP
$ReportFile = 'SystemReport_-_{0}.csv' -f $TimeStamp
$FullReportFile = Join-Path -Path $ReportPath -ChildPath $ReportFile

$NoResponse = '_n/a_'

$IC_ScriptBlock = {
    $CIM_CS = Get-CimInstance -ClassName CIM_ComputerSystem
    $CIM_BE = Get-CimInstance -ClassName CIM_BIOSElement
    $CIM_Processor = Get-CimInstance -ClassName CIM_Processor
    $CIM_OS = Get-CimInstance -ClassName CIM_OperatingSystem
    $CIM_Ram = Get-CimInstance -ClassName CIM_PhysicalMemory

    [PSCustomObject]@{
        ComputerName = $CIM_CS.Name
        ScanDate = [datetime]::Now.ToString('yyyy-MM-dd')
        UserName = $CIM_CS.UserName
        # this may be an array in a multi-processor system
        Processor = $CIM_Processor.Name
        ProcessorSpeed_Mhz = $CIM_Processor.MaxClockSpeed
        InstalledRAM_GB = [math]::Round(($CIM_Ram.Capacity |
            Measure-Object -Sum).Sum / 1GB, 2)
        Manufacturer = $CIM_CS.Manufacturer
        Model = $CIM_CS.Model
        SerialNumber = $CIM_BE.SerialNumber
        OS_Name = $CIM_OS.Caption
        OS_Version = $CIM_OS.Version
        OS_InstallDate = $CIM_OS.InstallDate.ToString('yyyy-MM-dd')
        }
    }
$IC_Params = @{
    ComputerName = $ComputerList
    ScriptBlock = $IC_ScriptBlock
    ErrorAction = 'SilentlyContinue'
    }
$RespondingSystems = Invoke-Command @IC_Params

$NOT_RespondingSystems = $ComputerList.Where({
    # these two variants are needed to deal with an ipv6 localhost address
    "[$_]" -notin $RespondingSystems.PSComputerName -and
    $_ -notin $RespondingSystems.PSComputerName
    }).
    ForEach({
        [PSCustomObject]@{
            ComputerName = $_
            ScanDate = [datetime]::Now.ToString('yyyy-MM-dd')
            UserName = $NoResponse
            Processor = $NoResponse
            ProcessorSpeed_Mhz = $NoResponse
            InstalledRAM_GB = $NoResponse
            Manufacturer = $NoResponse
            Model = $NoResponse
            SerialNumber = $NoResponse
            OS_Name = $NoResponse
            OS_Version = $NoResponse
            OS_InstallDate = $NoResponse
            }
        })

$RespondingSystems = $RespondingSystems |
    Select-Object -Property * -ExcludeProperty PSComputerName, PSShowComputerName, RunspaceId

$AllSystems = $RespondingSystems + $NOT_RespondingSystems

# show on screen
$AllSystems

# send to CSV
$AllSystems |
    Export-Csv -LiteralPath $FullReportFile -NoTypeInformation