Power supplies & cables glossary

The widest plug coming from the power supply, with 24 small holes in two rows. It goes into the right-hand edge of the motherboard and is stiff, so it's often left slightly loose. Push until its clip clicks.

Mentioned in: PC Won't POST · New PC Build Won't Turn On

A separate cable that powers the processor. It plugs into the top-left corner of the motherboard, near the processor, and is labeled "CPU" on the cable. It often splits into two 4-pin halves ("4+4"), and both halves must go in. Without it, the PC won't start.

Mentioned in: PC Won't POST · Motherboard Debug Lights Meaning · New PC Build Won't Turn On

Most graphics cards need extra power cables from the power supply, plugged into the top or end of the card. They have 6, 8 or 16 pins (the 16-pin type is called 12VHPWR or 12V-2x6). They look like the CPU cable but are labeled "PCIe" and aren't interchangeable.

Mentioned in: PC Turns On But No Display · Motherboard Debug Lights Meaning

On a modular power supply the cables unplug from the PSU itself, so you only use the ones you need. That means each cable has two ends to check: the PSU side and the part side. Some compact models split one cable into two plugs at the PSU end.

Mentioned in: PC Won't POST · New PC Build Won't Turn On

With the power supply unplugged from everything except the wall, a bent paperclip connecting two specific pins on its 24-pin plug makes it switch on. If its fan spins, the PSU is at least turning on. Many PSUs include a small tester plug that does the same job more safely.

Mentioned in: New PC Build Won't Turn On