Western Digital Ultrastar DC HC550 18 TB

This is a 18000GB 3.5" HDD on the SATA interface. At roughly $0.04 per gigabyte it sits in the premium tier. Sequential throughput tops out at 550 MB/s reads and 520 MB/s writes, backed by 512MB of cache. SATA throughput caps near 550 MB/s — fine for game libraries and backups, slower for heavy scratch work.

Its $694.45 price tag places it squarely in premium territory. PlanMyPC's builder flags compatibility problems automatically and tracks the latest drive deals from multiple stores. Support and warranty service run through Western Digital, with terms that vary by region. Scroll down for the complete spec table; the builder's compatibility checker will warn you about any conflicts with components you have already picked.