segfaultdotorg
macrumors 68000
I purchased my iMac used (no warranty) about six months ago. It has always made an off-and-on hissing noise when the display turns off but the computer remains on. When this happens, the lights in my room flicker. It sounds like a capacitor discharging, repeatedly. The computer will go into full sleep mode (display + CPU) without incident. Has anyone had this problem before? Does it sound like a power supply problem, or something else? Many thanks.