I decided the desktop needed a motherboard

My desktop had been having problems and eventually stopped working. Because the computer was down, I could not put ChatGPT into computer-use mode and ask it to inspect the machine directly. Instead, I described what had been happening before it died and worked through the possible causes in a normal chat. That reasoning led me to replace the motherboard.

The replacement improved the computer, and I still believe it was the right first decision, but one problem remained. This is the first half of the repair story. The motherboard did not make every symptom disappear, and I am not going to rewrite the sequence to make the first purchase look like a perfect one-step diagnosis.