What type of protection features does this breakout adapter module offer to prevent short circuits or overload?

PCB plastic spacer design for preventing short circuit.

Does this power adapter board support both 20-pin and 24-pin ATX power supplies?

Yes, the product title indicates that it is a 2pcs 20/24Pins ATX Benchtop Power Adapter Board, which means it supports both 20-pin and 24-pin ATX power supplies.

Questions & Answers: JMT 2pcs 20/24Pins ATX Benchtop Power Adapter Board with USB 5V Port Computer ATX Power Supply Breakout Adapter Module (Blue)

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JMT 2pcs 20/24Pins ATX Benchtop Power Adapter Board with USB 5V Port Computer ATX Power Supply Breakout Adapter Module (Blue)

Designed to take advantage of your power supply to create a benchtop power supply with 4 channel voltages to run almost any of your embedded electronics projects
Provide quick access to the typical voltages needed including 3.3V, 5V, 12V and -12V
Each output channel has replaceable 5A fuse and corresponding ground connection with binding post easy to connect
On-board standard 24pin ATX port, power indicator and power switch easy to control ideal to DIY low voltage power supply for developing physical computing projects (embedded systems)
PCB plastic spacer design for preventing short circuit .

$32^.59 –