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?
A newly installed graphics card is not detected at boot. Which action should the technician take FIRST?
A point-of-sale kiosk must accept input through thin gloves with a stylus. Which touchscreen technology is appropriate?
A user plugs several bus-powered devices into one port and Windows reports a USB power surge. What is the best remedy?