Screen darker at the top

Using an iMac with 2.66 GHz Intel Core 2 Duo and OS 10.6.7; bought in 2008

Today when I turned the 'puter on, the top of the screen has darkened to about a third of the way down. Still able to see everything but the top is definitely darker than the bottom; anything I can do to adjust this or is the screen going out?

Run this test for us: Take a screenshot of your desktop. Does the screenshot show the same thing?

If the screenshot shows the same, it's probably graphics related. If it doesn't, it's likely a display defect.

Post back results.

Screenshot looks the same as the desktop.

If the screenshot shows the same thing as you're seeing on the desktop, it's not the display. That tells us it has something to do with the graphics processor. The GPU on your model iMac is mounted to the logic board (motherboard) and if it is somehow acting up or defective, that would mean a logic board swap out.

Try starting your iMac in Safe Boot mode. (hold down the shift key as soon as you hear the POST chime) Is it doing the same thing in Safe Boot mode?

Also, is your iMac covered by Apple care? If it is, make an appointment with Apple and have them look at it.

The screen looks the same in Safe Boot mode; I think my Apple Care has run out; guess I'll have to take it in any way. Thanks for your help!

Just a quick heads up. My imac G5 iSight did that but toward the bottom. Difference is I had been inside fixing another issue with the Hard Drive.

One of the plugs from the LCD to the Bottom Inverter board pulled out a bit when I had lifted the display a bit to route some wires. So the bottom of the LCD was not being lit! Pushed it back in and like new!