PSU wattage, modular, 24-pin, and rails matching lab

Match wattage, modular, ATX 24-pin, and 12V-rail tickets; leave open-PSU and ignore-VAC unused.

Match each PSU ticket to the right fix. Leave open-chassis and ignore-VAC unused.

CompTIA 3.6 wants wattage, modularity, the ATX 24-pin, and rail awareness — plus the safety rule that you do not crack open a live supply.

New GPU; system reboots only under 3D load

Idle is fine. Load collapses. Capacity class, not a bad OS driver first.

SFF build: unused PCIe cables block airflow

You need the connectors you use — and freedom to omit the rest.

Board has no POST; CPU fan twitches once

Primary board power connector — not the GPU PCIe alone.

EPS + dual PCIe draw; 5V rail is huge, 12V is thin

Which rail actually feeds modern CPU/GPU power?

Still on the bench

Upsize wattage / headroom for GPU + drive load — Undersized PSU brownouts under load. Spec continuous wattage with margin — not the sticker peak fantasy.
Semi/fully modular cabling — pull only what you need — Modular lets you omit unused PCIe/SATA runs for airflow. Non-modular forces every cable into the case.
ATX 24-pin (20+4) mainboard power — seat fully — Primary board power is the 24-pin. A loose 24-pin looks like a dead motherboard.
Check 12V rail capacity for CPU/GPU EPS and PCIe — Modern builds starve on weak 12V. Rails matter more than a huge 5V rail nobody uses.
Open the PSU chassis to 'inspect the rails' with a meter — Never open a PSU — capacitors hold lethal charge. Measure at connectors, not inside.
Ignore 115/230 input switch — 'auto-detect always works' — Dual-voltage units with a wrong switch can let the smoke out. Confirm region input first.