first gen Imac 1.8 G5 "going bad" solution?

Our 5 year old Imac started having thatched squares on the screen after a few minutes being on. Doing some research showed it was a common problem on 5 year old G5's. I inspected the capacitors but didn't find any bulged ones.
Trying to isolate the problem area with a combination of cold spray on individual components and heat, I ran it with the back cover off. The cold spray didn't find anything but the G5 has been running fine for the last 3 days this way. If I put the cover back on, the problem re-appears. So, looks like a heat issue. I'll be using it this way until I can, if ever, find the exact spot or component that's causing the problem but I wonder how many G5's have been scrapped when this is a simple solution. I'll make a small set of stands or legs out of wood so it safer and the speakers resonate more but otherwise, even if it is an older G5, it's good enough for surfing the net and running other tasks..

It might also be some sort of a short caused when the case is on..but I have to say that is a very odd thing to have happen. Most people wouldn't really bother with extreme troubleshooting or running it like that, especially when it's 5 years old, but hey it still works right? ;D

Update:
I put the back on and... it works just fine. The only thing I did besides testing the unit with cold-heat was to clean the fans with compressed air. Lots of dust there.
So.. it has nothing to do with the cover on or off..
Yes it's old, by today's standards but it's such a great looking design I'd probably turn it into an aquarium rather than throwing it it out. Anyhow, for what my wife uses it for (surfing the net) it does the job. (we're now using a G4 power Mac instead)
Also, I like to get my money's worth. At the price it cost 5 years ago, I figure I should get a few more years out of it...

AylmerQc said:

Update:
I put the back on and... it works just fine. The only thing I did besides testing the unit with cold-heat was to clean the fans with compressed air. Lots of dust there.

Click to expand...

WOW...that's a pretty positive outcome!

It's possible that the dirt/dust was blocking the cooling pathways, causing the computer to run extra hot...and thus the problems.

Thanks a bunch for the update...I hope that your computer repair is long lasting!

- Nick

Well, thinking about the whole thing, I think shooting very cold spray on the caps might, just might have something to do with it, it it wasn't the fans,,

Put my money on dust clogging and slowing down the fans. Dust in iMacs in particular are big troubles.