Peripheral Devices & Expansion Cards
Key Takeaways
Input devices (keyboard, mouse, touchscreen, scanner, webcam, mic, barcode/signature/smart-card readers) connect via USB, Bluetooth, or 2.4 GHz wireless.
A KVM (Keyboard, Video, Mouse) switch lets one set of peripherals control multiple computers — common in server rooms.
Common expansion cards (GPU, sound, NIC, USB, capture, RAID controller) install in PCIe slots sized x1 to x16.
Plug-and-play lets modern operating systems auto-detect and configure most peripherals without manual driver installs.
For an unrecognized USB device, follow a structured path: try another port, check Device Manager, test on another PC, and verify power.
Input Devices
| Device | Connection | Use Case / Exam Note |
|---|---|---|
| Keyboard | USB, Bluetooth, 2.4 GHz RF | Primary text input |
| Mouse / trackpad | USB, Bluetooth, 2.4 GHz | Pointing |
| Touchscreen | Built-in (capacitive or resistive) | Capacitive = multi-touch, finger; resistive = pressure/stylus, kiosks |
| Flatbed scanner | USB | Uses TWAIN/WIA driver standards |
| Barcode / QR scanner | USB, Bluetooth, RF | Retail, inventory |
| Webcam / microphone | USB, 3.5 mm, built-in | Conferencing |
| Drawing tablet | USB, Bluetooth | Pressure-sensitive design input |
| Smart-card reader | USB, built-in | CAC/PIV authentication |
| Signature pad / fingerprint reader | USB, built-in | Capture and biometric auth |
| NFC reader | USB, built-in | Tap-to-pay, badge access |
Connection traits to know: Bluetooth is short range (~10 m Class 2) and must be put into pairing/discoverable mode on both ends. A 2.4 GHz RF keyboard/mouse uses a tiny USB dongle and is not the same as Bluetooth — losing the dongle means losing the device. Capacitive vs. resistive touchscreens is a recurring distractor: capacitive needs a conductive touch (your finger) and supports multi-touch; resistive responds to any pressure including a stylus or gloved finger.
Output Devices
| Device | Connection | Use Case |
|---|---|---|
| Monitor | HDMI, DisplayPort, USB-C, VGA (legacy) | Visual display |
| Projector | HDMI, VGA, USB-C, wireless | Large-format presentation |
| Speakers / headset | 3.5 mm, USB, Bluetooth, HDMI | Audio out |
| Printer | USB, Ethernet, Wi-Fi, Bluetooth | Document output |
Some devices are both input and output: a touchscreen displays and accepts input, and a multifunction printer prints, scans, copies, and faxes.
Expansion Cards
| Card | Typical PCIe Slot | Purpose |
|---|---|---|
| Graphics card (GPU) | x16 | Rendering, gaming, multi-display |
| Sound card | x1 | Higher-fidelity / surround audio |
| Network card (NIC) | x1 or x4 | 2.5/10 GbE wired or Wi-Fi 6E/7 |
| USB expansion | x1 | Add USB-A / USB-C ports |
| Video capture card | x1 or x4 | Capture HDMI input for streaming |
| RAID/HBA controller | x4 or x8 | Hardware RAID for many drives |
| Thunderbolt add-in | x4 | Adds Thunderbolt to a desktop |
A card needs enough electrical lanes: a GPU expects x16, but a x16 card runs in an open-ended x4/x8 slot at reduced bandwidth. A x1 card fits any larger slot.
Expansion Card Installation (ESD-safe procedure)
- Power off, unplug the PSU, and hold the power button to drain residual charge.
- Wear an anti-static wrist strap bonded to the chassis (ESD damage can be invisible and intermittent).
- Open the case and locate the correct PCIe slot for the card's lane count.
- Remove the rear slot bracket/cover.
- Align and firmly seat the card until the retention clip clicks.
- Secure the bracket with a screw or clip.
- Connect required power (most GPUs need 6+2 pin or 12VHPWR PCIe power).
- Close the case, power on, and install the latest driver.
Exam Tip: A new card that is not detected is almost always a physical seating or power issue — reseat the card and confirm the PCIe power connector is plugged in before reinstalling drivers or the OS.
KVM Switches
A KVM (Keyboard, Video, Mouse) switch lets one keyboard, monitor, and mouse drive several computers.
| Feature | Detail |
|---|---|
| Ports | 2, 4, 8, or 16 systems |
| Video supported | VGA, DVI, HDMI, or DisplayPort |
| Switching method | Hotkey, front button, or on-screen display (OSD) |
| Benefit | Saves desk space and the cost of duplicate peripherals |
| Use case | Server rooms, NOCs, multi-PC workstations |
Troubleshooting Peripherals
Apply the CompTIA troubleshooting methodology: identify the problem, establish a theory, test it, fix, verify full functionality, then document.
| Symptom | Structured Resolution |
|---|---|
| USB device not recognized | Try another port; check Device Manager for a yellow ! ; update/reinstall driver; test the device on another PC to isolate device vs. port |
| "USB power surge / hub exceeds" | Device draws too much current — use a powered USB hub or a direct port |
| Bluetooth won't pair | Put both ends in discoverable mode; remove old pairing; restart the Bluetooth radio |
| No audio output | Confirm the correct playback device is default; check mute/volume; update the audio driver |
| Wireless mouse/keyboard lag | Replace batteries; re-seat the 2.4 GHz dongle; move away from interference |
| Second monitor not detected | Reseat the cable; try another port; press Win+P to extend; update the GPU driver |
| Scanner not found | Verify the WIA / TWAIN driver and that the scanner service is running |
General rule: Always start with the simplest, least invasive check. Swapping the cable/port or rebooting beats reinstalling Windows. Confirm whether the fault follows the device or stays with the port — that single test isolates most peripheral issues.
What does a KVM switch allow an administrator to do?
Share one internet connection among many devices
Encrypt data on external drives
Convert analog video to digital
Control multiple computers with a single keyboard, monitor, and mouse
A newly installed graphics card is not detected at boot. Which action should the technician take FIRST?
Reinstall the operating system
Update the motherboard BIOS
Reseat the card and confirm its PCIe power connectors are plugged in
Replace the card with a different model
A point-of-sale kiosk must accept input through thin gloves with a stylus. Which touchscreen technology is appropriate?
Resistive
Capacitive
Infrared multi-touch
Surface acoustic wave
A user plugs several bus-powered devices into one port and Windows reports a USB power surge. What is the best remedy?
Reinstall the chipset driver
Disable USB selective suspend
Switch the cable to USB 2.0
Use a powered (self-powered) USB hub
Sections you finish are checked off in the contents.