Video cards or video display adapters control the computer monitor. Power Supply Power supplies are most often found mounted at the rear of the case. They can range from 150 to over 200 watts depending on anticipated use. Most have output voltage of 5-12 volts. Power supplies contain fans that move air across the components to keep them cool.
Fans are a common failure point.
Do not attempt to repair a faulty power supply. Even units that have been off for sometime can hold a dangerous charge. RAM Random access memory is the key to a properly functioning computer system. ROM ROM chips contain instructions, which are specific for that particular motherboard. Primarily the ROM code holds start-up instructions.