What to replace in old iMac?

[Sw1428]

Hi everyone,

My father recently upgraded to a new iMac and gave me his old one. I restored the system and updated to OS X 10.7.5 (Lion).
When using the computer, the screen always seems to glitch, though. While on websites, a part of the screen will freeze in place while the rest works (when scrolling or attempting to watch a video). When switching spaces, the entire computer will freeze and I'll get the spinning wheel for a minute or two before it loads (during which, I only have one program open with a window in each space). Lines will randomly appear on the screen that are only a few pixels thick, but long horizontally.
Being as old as it is, I'm not surprised by the issues and expected some. I'm just wondering if there are any specific parts I can replace to get it up and running normally again. Since the computer is out of warranty and was free to me, I don't have an issue taking it apart and replacing parts, so any advice is welcome.
If any more information is needed, I'll do my best to provide it.
Thanks in advance!


iMac 6,1
24-inch, Late 2006

Processor 2.16 GHz Intel Core 2 Duo
Memory 4 GB 667 MHz DDR2 SDRAM
Graphics NVIDIA GeForce 7300 GT 128 MB
Storage 1.5 TB SATA Disk

 

[r6mile]

2006-2007 iMacs are notorious for overheating GPU issues, which is what's causing your horizontal lines (just google 2006 iMac horizontal lines and you'll see). There is nothing you can do about this other than replacing the logic board, which will cost many multiples of what the computer is worth and no guarantees that the problem won't arise again.

 

[Sirmausalot]

All of it.

 

[Sw1428]

2006-2007 iMacs are notorious for overheating GPU issues, which is what's causing your horizontal lines (just google 2006 iMac horizontal lines and you'll see). There is nothing you can do about this other than replacing the logic board, which will cost many multiples of what the computer is worth and no guarantees that the problem won't arise again.

Thanks! Maybe I can find a cheap one on Ebay or something and replace it on my own. If not, it's fine. Thanks again.

 

[briloronmacrumo]

There is nothing you can do about this other than replacing the logic board...

Haven't tried to replace just the GPU on this machine, so I'm not sure if the logic board also needs replacing(Mactracker does show the GPU as a separate card and not integrated on the logic board). The Mactracker app shows this machine's estimated price as $267.88 ( USD ) but NVIDIA GeForce 7300 GT on eBay are selling for less than $100. It also has the slower 1.5 Gbps SATA HD interface ( 6 Gbps is standard now ), so an SSD might help a little, but that slow interface will throttle the SSD. I would take a visit to iFixit.com and OWC for their tutorials. Personally, I'd replace the GPU and see what happens if you can get the part at this low cost. Might be fun.( be careful: some used parts are sold with issues - often disclosed )

Here is the iFixit page for that machine: https://www.ifixit.com/Device/iMac_Intel_24"_EMC_2111

 

[Johnny365]

So is it the Geforce GPU or the Radeon X1600 in the same late 2006-2007 line? I heard the pixel lines are caused by the screen (which resolve itself after getting a replacement screen), connection to the screen, GPU overheating/not enough heat dissipation, you name it. Has it been specifically notated that it's caued by the GPU overheating and is it preventable early on by using a fan pointed to the back of the iMac?