220-1201 · Hardware · Updated July 26, 2026
PC Cable and Connector Types: From USB and Video to Legacy Molex Power
Every connector in a PC is built for one of four jobs: moving data between the computer and peripherals or drives, carrying video to a display, delivering power, or linking the machine to a network. Identify the job first and the connector family follows — USB and SATA for data, HDMI and DisplayPort for video, the ATX family plus SATA power and legacy Molex for power, and RJ45 for wired Ethernet. The 220-1201 exam tests this recognition directly, often as a matching exercise where you sort a pile of connectors to their purposes. Recognition only comes from repetition — drilling practice questions until identification is instant is the shortest route.
The master matching table
This is the sorting exercise in one place — connector, family, and the job it is designed for.
| Connector | Family | Designed for |
|---|---|---|
| USB-A | Data | Classic rectangular host port for keyboards, mice, flash drives |
| USB-B | Data | Squarish device end on printers and scanners |
| USB-C | Data/video/power | Reversible do-everything port: data, DisplayPort Alt Mode video, USB Power Delivery charging |
| Micro-USB / Mini-USB | Data | Older phones, cameras, and portable devices |
| Lightning | Data | Apple’s proprietary reversible connector on older iPhones/iPads |
| Thunderbolt 3/4 | Data/video/power | USB-C-shaped high-speed interface (40 Gbps) for docks and external GPUs |
| HDMI | Video | Consumer video + audio to TVs and monitors |
| DisplayPort | Video | PC-centric video + audio; supports daisy-chaining monitors |
| DVI | Video | Legacy digital (and DVI-I analog) monitor connections |
| VGA (DE-15) | Video | Legacy 15-pin analog video, often on projectors |
| SATA data (7-pin) | Storage data | Connects internal HDDs/SSDs/optical drives to the motherboard |
| SATA power (15-pin) | Power | Powers SATA drives from the PSU |
| Molex (4-pin) | Power | Legacy PSU connector for optical drives, older PATA hard drives, case fans |
| 24-pin ATX | Power | Main motherboard power from the PSU |
| 4/8-pin EPS | Power | Dedicated CPU power near the socket |
| 6/8-pin PCIe | Power | Supplemental graphics-card power |
| RJ45 (8P8C) | Network | Twisted-pair Ethernet to a switch, router, or wall jack |
| RJ11 (6P2C/6P4C) | Network/telecom | Telephone and DSL lines — narrower than RJ45 |
USB: one name, many shapes and speeds
Universal Serial Bus (USB) is the default peripheral interface, and the exam expects you to keep shapes and speeds straight. USB-A is the flat rectangle on the host side; USB-B and its micro/mini variants live on the device side of printers and older gadgets. USB-C replaced the lot with one small reversible oval that can carry USB data at any generation’s speed, video via DisplayPort Alternate Mode, and up to 240 W of charge through USB Power Delivery (PD).
Speed milestones worth memorizing: USB 2.0 at 480 Mbps, USB 3.x from 5 Gbps to 20 Gbps, USB4 up to 40 Gbps. Thunderbolt 3 and 4 use the USB-C connector but layer on guaranteed 40 Gbps bandwidth and PCI Express tunneling, which is what lets a single cable drive a dock with displays, Ethernet, and storage. A cable’s connector shape alone doesn’t reveal its capability — a cheap USB-C cable may be USB 2.0 inside — so match the cable’s rating to the task when troubleshooting slow transfers or docks that won’t drive monitors.
Video: HDMI, DisplayPort, and the legacy pair
High-Definition Multimedia Interface (HDMI) is the consumer standard — TVs, monitors, game consoles — carrying digital video and audio on one cable. DisplayPort (DP) is the PC-side equivalent, favored for high refresh rates and multi-monitor daisy-chaining via Multi-Stream Transport (MST); its latch-equipped connector distinguishes it from HDMI’s friction fit — differences that matter when a monitor reports no signal. Digital Visual Interface (DVI) came before both: digital-only (DVI-D) or digital-plus-analog (DVI-I) with a wide pin block. Video Graphics Array (VGA) is the blue 15-pin trapezoid carrying purely analog signal — still found on projectors and legacy KVMs, and the giveaway that image fuzziness may be cable/signal related, since analog degrades where digital either works or doesn’t. Marginal or damaged video cables of any type are also a classic cause of monitor flickering.
Power connectors: ATX family, SATA power, and Molex
From the power supply unit (PSU), power reaches components over a small set of keyed connectors. The 24-pin ATX main connector feeds the motherboard; the 4/8-pin EPS connector delivers dedicated CPU power; 6/8-pin PCIe connectors (and the newer 12V-2x6/12VHPWR on current GPUs) feed graphics cards; and the flat 15-pin SATA power connector runs modern drives.
The one legacy connector CompTIA still names is Molex — the chunky white 4-pin peripheral connector with two black (ground), one red (+5 V), and one yellow (+12 V) wire. Molex was the standard power feed for optical drives, Parallel ATA (PATA/IDE) hard drives, and case fans for decades. You’ll still meet it on older systems and as an adapter source when a PSU runs out of SATA power leads. When an exam stem asks which legacy power connector originally served optical drives and peripherals, Molex is the answer — SATA power is its modern replacement. For what each wire color’s voltage rail actually powers, see redundant power supplies and PSU voltage rails.
Storage and network: SATA data, RJ45, RJ11
The 7-pin SATA data cable is the thin L-keyed ribbon linking internal drives to motherboard SATA ports — data only; the drive still needs its separate 15-pin power connection. External SATA (eSATA) extends the same interface outside the case, though USB has largely displaced it.
On the network side, RJ45 (technically an 8P8C modular plug) terminates twisted-pair copper Ethernet — the connector you crimp onto Cat 5e/6/6a cable. RJ11 looks like its little sibling: narrower, with fewer conductors, used for analog telephone lines and Digital Subscriber Line (DSL) modems. Plugging a phone cord into an Ethernet jack is a classic user mistake precisely because the shapes are so similar; RJ11 seats loosely in an RJ45 port and connects nothing.
How the 220-1201 exam tests this
- Matching/PBQ format: you’re handed six to eight connectors and a list of jobs — pair Molex with legacy optical-drive power, SATA data with an internal SSD, RJ45 with Ethernet, USB-C with charging plus display output, VGA with an aging projector. Work by elimination: place the unambiguous ones (RJ45, VGA) first.
- “Which legacy power connector…?” Molex is the expected answer for optical drives and older peripherals; distractors will be SATA power (modern, not legacy), Berg/floppy, and the 24-pin ATX.
- Same shape, different capability: stems distinguish Thunderbolt from plain USB-C, or explain why one USB-C cable charges a laptop while another won’t — the connector is identical; the cable’s PD and data ratings differ.
- RJ45 vs. RJ11: expect a scenario about a DSL line or phone jack; the narrower connector with fewer pins is RJ11.
Quick reference
- Sort connectors by job: data (USB, SATA), video (HDMI, DP, DVI, VGA), power (ATX, EPS, PCIe, SATA power, Molex), network (RJ45, RJ11).
- Molex = legacy 4-pin peripheral power (+5 V red, +12 V yellow) for optical drives, PATA disks, and fans.
- SATA drives need two connections: 7-pin data plus 15-pin power.
- USB-C is the shape; USB4, Thunderbolt, Power Delivery, and DP Alt Mode are capabilities that may or may not be present in a given cable.
- USB 2.0 = 480 Mbps; USB 3.x = 5–20 Gbps; USB4/Thunderbolt = up to 40 Gbps.
- DisplayPort daisy-chains monitors (MST) and latches; HDMI dominates TVs; VGA is analog-only.
- RJ45 (8 conductors) = Ethernet; RJ11 (fewer conductors, narrower) = telephone/DSL.