IMac – Why there is a black spot in the display of the iMac

I would go back to the Apple store to speak with a technician again. Apple repair service has historically been warranted for 90 days or the remainder of the existing coverage (one year or three from original purchase if you have AppleCare) so if you are outside the first year the numbers don't add up. It should be written on the back of the quote they provided you. They might even give you some options for other local service providers that have passed the hardware repair tests to work on Macs but you can always look them up yourself.

The internal LCD panels for that model are integrated with a frame, and a driver board so you're not just buying a commodity 24" LCD panel. You are also buying expertise in case it's not the LCD panel but a video card or the cable. I don't know of many shops that can beat Apple's current labor rates of $39 so you would hope to get a good feeling about why the shop can beat apple's price so much on parts. I always feel better when a shop can explain to me why the parts they use are cheaper than the manufacturer's parts so I can make a good decision.

It's not as hard a repair as say the graphics card or the logic board in that model, but you'll find lower labor rates and better parts prices from shops that do a high volume of that model repair.

Once you've got some quotes you can make a better call in your situation - it might make sense to buy an external monitor even if it's more costly that the repair - especially if that investment will carry forward to an eventual new mac.

As you have seen, all Apple products actually run even when you power them off. On iOS, the battery keeps time and on Macs, the SMC is responsible for knowing when the power button is pressed and if the Mac should start itself up due to a scheduled wake or power on being saved in the NVRAM.

If you called for service, Apple would likely focus on several things:

1. Have you checked that the firmware and software is up to date.
2. Does this happen every single time, or is it an occasional thing.
3. Have you disconnected everything (including the mouse and keyboard) and tested to see if it's in any way related to a peripheral.

Assuming you can reproduce this at will (it happens every time), you would probably take steps to reset the SMC to ensure it's getting proper readings from the temperature sensors.

• Intel-based Macs: Resetting the System Management Controller (SMC)

If after spending the 10 minutes it would take to read through each and every step (I feel it's important to perform the steps in order - even if they seem unrelated or unnecessary), I would expect them to want to run diagnostics to physically open the Mac to check the sensors and wiring. Your symptoms sure sounds like the SMC either is stuck in some loop and not reading the temp sensors. Failure to control the fans properly could also be a hardware issue where the SMC is receiving a signal where the correct action is to keep the fans not only spinning, but spinning at an elevated level.