Line through display

[pensfan]

My iMac has recently begun to slow down frequently, where I get the spinning beach ball and can't do a thing for periods at a time. This is intermittent, but it is more and more frequent.

Something I've noticed that has begun to occur around this same time is that occasionally, I'll have a white line going through the middle of the display. If there are windows open (like a browser window), it usually goes through that. If I'm in a browser and I hit refresh, it goes away. However, I can take a screen shot and capture the image.

Does this suggest a motherboard issue or graphics card failure? Or is it something else, perhaps?

Thanks for your suggestions,
Kevin

[DeltaMac]

Is that a vertical line, or horizontal?

[pensfan]

It is horizontal, approximately mid-screen, though it will sometimes be higher or lower.

[DeltaMac]

You can run the Apple Hardware Test diagnostics. You boot to that test by inserting your original Restore DVD (one of the set of two DVDs that came with your iMac when new), and restarting while holding the D key on your keyboard. Run the extended test.

Check that your cooling vents are open, especially the small round one underneath the hinge, above the power connector port. It's one that most people miss.
However, a horizontal line is not necessarily a hardware problem.
Test your hard drive: Boot to your Snow Leopard installer DVD.
Choose Disk Utility from the Utilities menu.
Run Repair Disk (not Repair Disk Permissions.

What is the result?

[pensfan]

Thanks, DeltaMac. I'm not sure if I should be pleased or unhappy, but it passed the Disk Utility test when booted off the Snow Leopard disk and it reported no trouble when running the extended test on the AHT when booting from the restore DVD.

So does this suggest software, or can there be other hardware issues that are not being detected?

[DeltaMac]

Do you ever run one of the system utilities, such as OnyX?
You can try using that to clear various caches in the system, and you may get a better running Mac.
New slow downs in OS X should be watched. You can monitor your Activity Monitor (in your Utilities folder), with All Processes chosen from the drop-down menu. Watch to see if any processes take large amounts of CPU or memory, when you get the slow-downs. You would also be watching the memory tab (along the bottom of that window) for large amounts of page-outs. That means that your Mac is sending swapouts to the hard drive, as it's running completely out of memory. That can dramatically slow down your Mac while that is happening.

[djackmac]

I've seen plenty of those iMacs with the same symptoms. It's usually the LCD panel needs replaced. To verify try to connect to an external monitor and mirror the display to verify. If it doesn't show on external its the LCD. If it does show externally its possibly the GPU or maybe software.