CompTIA Exam Prep - ITF+, A+, Network+, Security+, CySA+

The power supply converts mains AC into the DC rails a computer needs. The A+ exam covers the connector types, efficiency ratings, sizing and — most usefully — how to recognise a failing one. Modular, semi-modular, non-modular Type Cables Suits Non-modular All permanently attached Budget builds; cheapest Semi-modular Essential cables fixed, rest detachable Most builds; good balance Fully modular Every cable detachable Small cases, custom builds, servicing The advantage of modular is cable management: you connect only what you need, so there is less clutter, better airflow, and easier building in a small case. The disadvantages are slightly higher cost and one additional connection point per cable. The critical warning, and a genuine exam item: modular cables are not interchangeable between manufacturers or even between models from the same manufacturer. The connector on the PSU side may be physically identical while the pinout differs, and connecting the wrong cable can put 1...

The socket is the mechanical and electrical interface between processor and motherboard. The A+ exam tests the socket types, correct installation, and what goes wrong. LGA, PGA and BGA Type Pins on Used by Replaceable LGA — land grid array The socket Intel desktop, AMD AM5 Yes PGA — pin grid array The processor AMD AM4 and earlier Yes BGA — ball grid array Soldered Laptops, mobile devices No LGA puts the contacts in the socket as spring-loaded pads, and the processor has flat gold lands on its underside. Bend a pin and you have damaged the motherboard, not the CPU. PGA puts the pins on the processor and the holes in the socket. Bend a pin here and you have damaged the CPU. That reversal is the whole exam point, and it has a practical consequence: with LGA, treat the socket as the fragile part and never touch the contact array; with PGA, treat the processor as fragile and always set it down on its top surface. BGA is soldered directly to the board. Not user-replaceable, wh...

The digitizer is the layer that converts physical touch into coordinates the operating system can use. On the A+ exam it appears in mobile device repair, and the testable skill is separating a digitizer fault from a display fault. The layers of a screen A modern laptop or phone screen is a stack, and knowing the order explains every symptom. Protective glass — the outermost layer you touch. Digitizer — the touch-sensing layer. Display panel (LCD or OLED) — produces the image. Backlight — on LCD panels only; OLED pixels emit their own light. Inverter — on older CCFL-backlit LCDs, converting DC to the AC the lamp needs. LED backlights do not use one. The digitizer sits above the display. That is why you can have a perfect image with no touch response, or working touch with a black screen. Separating the symptoms This is what the exam asks, in scenario form. Symptom Likely fault Image fine, touch dead or erratic Digitizer Touch works, no image at all Display panel or b...

A SODIMM — Small Outline Dual In-line Memory Module — is the memory module used in laptops, small form factor desktops, all-in-ones, printers and many network appliances. Same DDR memory as a desktop, in a shorter package. The A+ exam tests three things: telling a SODIMM from a DIMM, matching pin counts to DDR generations, and installing one without damaging it. SODIMM versus DIMM Aspect DIMM SODIMM Length about 133 mm about 67 mm Used in Desktops, servers Laptops, SFF, all-in-ones DDR4 pins 288 260 DDR5 pins 288 262 Installation Straight down, clips at both ends Angled in, then pressed flat They are not interchangeable in either direction. A SODIMM will not seat in a desktop slot, and a DIMM will not fit a laptop. Pin counts — the memorisation item These come up directly, so learn the table. Generation SODIMM pins DIMM pins DDR2 200 240 DDR3 / DDR3L 204 240 DDR4 260 288 DDR5 262 288 Note that DDR3 and DDR4 DIMMs both have 240 and 288 pins respectively while their ...

M.2 is a form factor, not a protocol. That single sentence resolves most of the confusion around these drives, and it is what the A+ exam is really testing. An M.2 slot is a physical connector on the motherboard. What runs across it may be SATA or NVMe, and the performance difference between the two is large. NVMe versus SATA over M.2 M.2 SATA M.2 NVMe Protocol SATA (AHCI) NVMe over PCIe Speed ceiling about 600 MB/s 3,500 MB/s and far beyond Typical keying B+M (two notches) M only (one notch) Queue depth 1 queue, 32 commands 65,535 queues An M.2 SATA drive is capped at the same 600 MB/s as any other SATA III device, because it is using the SATA protocol — the connector changed, the bus did not. NVMe talks directly over PCIe lanes and skips the translation layer that AHCI imposes, which is why it is several times faster. The deep queue matters more than the headline sequential number. AHCI was designed for spinning disks with one head; NVMe was designed for flash that can ser...

SATA is one of those topics the A+ exam keeps coming back to, because almost every desktop and laptop you will ever open has a SATA device in it or a slot where one used to be. Serial ATA replaced the old Parallel ATA ribbon cables in the mid-2000s and stayed the default storage interface for two decades. The exam does not ask you to design a storage controller. It asks whether you can identify a connector on sight, quote the speed of a revision, and work out why a drive is not showing up. What SATA actually is SATA is a point-to-point serial interface between a host controller and a single storage device. Two words in that sentence matter. Serial means one bit at a time down a differential pair, rather than sixteen bits in parallel down a ribbon. That sounds slower, and per-wire it is, but serial links can be clocked far higher because you are not fighting to keep sixteen signals in step with each other. Parallel ATA topped out at 133 MB/s. SATA started at 150 and went up from t...