Purge non-existent PCs from SCCM - Improper maintenance tasks?

Hi Guys,

I didn't set up our SCCM maintenance tasks, but we have an annoying issue with systems still in SCCM that haven't been turned on in months (or years). These are our settings:

Delete Obsolete Client Discovery data = 61 days

Delete Aged Computer Association Data = 1 day

Delete Aged Discovery Data = 62 days

Delete Inactive Client Discovery Data = 28 days

One of the issues is our AD isn't kept up to date, so SCCM will keep on detecting non-existent PCs. Many of these haven't been turned on in months (or even years). If a PC no longer exists, but is in AD then I get why they would still show up in the console. But what we'd like to do is if a PC hasn't been turned on in 3 (or 6 months) to remove the hardware/software inventory of the client. A big reason is for reporting capabilities. Systems that once had software licensed will show up and could cost us money.