Expansion Cards, Storage, Power Supplies

• PCIe (PCI Express) is the standard for GPUs and other high-speed cards.
• PCIe x16 provides the highest bandwidth for video cards.
• PCIe is a serial bus and is faster than older parallel buses.
• M.2 is a form factor for NVMe or SATA SSDs.
• NVMe is the fastest storage protocol (about 3.5–4 GB/s).
• SATA 3 is about 600 MB/s. PATA/IDE is legacy (40-pin, obsolete).
• A NIC (Network Interface Card) connects a device to a network.

• Fastest to slowest: PCIe (~4.0 GB/s) → M.2/NVMe (~3.5 GB/s) → SATA 3 (600 MB/s) → SATA 2 (300 MB/s) → SATA 1 (150 MB/s) → PATA (legacy).
• HDD = mechanical, slower. SSD = no moving parts, faster. NVMe = newest/fastest standard.
• Optical drives (DVD, Blu-ray) are declining. Memory cards (SD, microSD, CompactFlash) are for cameras. USB flash drives are portable storage.

• Single-sided, single-layer Blu-ray ≈ 25 GB.
• Double-sided, single-layer DVD+R ≈ 9–10 GB.
• DVD+R/DVD-R single-layer ≈ 4.7 GB.
• CD ≈ 700 MB.
• A 20 GB video file needs a larger format than single-layer DVD.

Wall outlet is AC. The computer needs DC. The PSU converts AC → DC. Reversing input/output is a common exam mistake.

• Standard PC voltages: +3.3V DC, +5V DC, +12V DC, −12V DC (rarely used).
• Not standard: +4.3V, +8V, +110V as DC rail values.
• Wattage varies (100W, 500W, 850W) and must match system needs. Voltage conversion stays AC→DC.
• Redundant PSU = backup if the primary fails; critical on servers. Often one on / one standby.

• Hot-swappable: power does not need to be turned off before insert/remove (USB, many external drives, some bays).
• Hot-swap is not the same as yanking a drive immediately after shutdown while it is still spinning/hot.
• Modern internal HDDs do not need a separate external power source; the PSU has capacity.
• Match form factor. Secure with at least two screws (one per side; preferably two each side). Do not block airflow with cables.

• RAID 5: minimum 3 drives, striping with parity, survives one drive failure.
• Rebuild time can be hours to months in enterprise — a real operational challenge.
• Discrete video: PCIe x16 is the standard. Can coexist with integrated video (may disable IGP in BIOS).
• PCIe cards are usually auto-detected; still install the correct driver.
• PCIe x128 is not a real standard. AGP is obsolete. Plain PCI is too slow for video.