I just re-sleeved some old cards the other day. The 30 year old sleeves were pretty rough. 😛
May be a good idea to run Memtestbefore sunsetting it. HDDs are harder to test but the SMART information may help some
For the CPU, you’ll want Prime95
Granted, Prime95 is mostly for stress testing but could let you know if something is going belly up.
For GPU’s, you’ll definitely want FurMark. 🙂