Are used enterprise SSDs worth the power savings?

Running TCO for a 24-bay storage node at a Contabo colo. Power is €0.14/kWh with a 15A limit per rack.

• Spinning rust: 12W idle, 18W load per drive. 24 drives = 288W-432W. 3 years = $1,063-$1,594 power only.
• Used Intel S3710 400GB: 1.5W idle, 3W load. 24 drives = 36W-72W. 3 years = $133-$265.

Route via spinning rust adds 12ms avg seek.
Route via S3710 adds 0.05ms.

But these drives are 5-7 years old, 10 DWPD spec, unknown wear. $18/drive used versus $85 new SMR rust.

The power savings alone pay for replacement in 18 months. But do they actually survive 18 months?

What firmware gotchas am I missing? Do I need vendor tools to unlock wear info, or does SMART tell the truth?

SMART lies on Intel enterprise. Check power-on hours against write amplification, not wear percentage. Locked if firmware mismatch with HBA. Take vendor tools to DMs.