System Health Check Script

1. Get-WmiObject -Computername localhost -Class Win32_PerfFormattedData_PerfOS_Memory

2.  Get-WmiObject -Computername localhost -Class Win32_PerfFormattedData_Counters_ProcessorInformation

3. Get-WmiObject -Computername localhost -Class Win32_LogicalDisk

Play with those objects to find what You need