Hardware
What to know
Hardware questions test compatibility and capacity math. CPUs must match the socket (LGA vs PGA/AM4) and chipset; RAM must match generation, form factor, and speed, and motherboards have a maximum capacity and channel configuration. Storage: HDDs are mechanical and slow, SATA SSDs cap near 6 Gb/s, and NVMe drives use PCIe lanes for far higher throughput. RAID: 0 stripes with no redundancy, 1 mirrors, 5 stripes with parity (minimum three drives, survives one failure), 10 mirrors then stripes (minimum four drives, 50% capacity).
Power and expansion: check PSU wattage and connectors (24-pin main, 4/8-pin EPS for CPU, PCIe for GPUs), and match card size to slot length. Firmware: UEFI replaces BIOS, supports GPT partitions (over 2 TB, many partitions) and Secure Boot; legacy MBR is limited to 2 TB and four primary partitions.
Printing: laser printers go charging, exposing, developing, transferring, fusing, cleaning - in that order; the fuser is hot. Inkjet uses liquid ink and clogs if unused; thermal printers need special paper; impact printers use ribbons for multipart forms.
Traps. RAID 0 is not fault tolerant despite being “level 0”; RAID 5 survives only one drive failure. DDR4 will not fit a DDR3 slot. An M.2 slot may be SATA-only. Thermal paste goes between CPU and heatsink - a common “overheating after reassembly” answer.
Rule of thumb. Capacity: RAID 5 usable = (n−1) × smallest drive; RAID 10 = 50% of total; RAID 1 = capacity of the smallest drive.
Worked example. Four 2 TB drives: RAID 5 gives 6 TB usable and tolerates one failure; RAID 10 gives 4 TB usable and tolerates one failure per mirror pair.