When sourcing refurbished CPUs, technical reliability is paramount. You must ensure the supplier performs rigorous stress testing using industry-standard software like Prime95 or AIDA64 for at least 24 hours to ensure stability under load. Verify that the CPU pins (for PGA) or contact pads (for LGA) are free from oxidation, scratches, or thermal paste residue. Additionally, request CPU-Z screenshots to confirm that the specifications (clock speed, cache, and stepping) match the original manufacturer's data sheet.