Imac G5 stripes of white lines in normal mode start

You could try & see if a reset of the power management chip in your G5 iMac

may help; but there is a likelihood a hardware issue or component failure is

behind the symptoms you've experience in that model build series.

• iMac G5: How to Reset the SMU - Apple Support

If yours is an original iMac G5 the power management reset varies; note detail

in the above support article, about the location of a button on the early model.

Another support article about iMac G5 issues, troubleshooting, reset, etc.

• iMac G5: Troubleshooting when your computer won't turn on - Apple Support

Not sure if a PRAM-NVRAM reset could help because a few symptoms can be

affected by either or power/system management controller reset or PRAM...

• How to Reset PRAM-NVRAM on your Mac - Apple Support

Did you try booting from the installer disc to see if any symptoms in display

went away? That could mean something in the way of troubleshooting...

There are possible graphics issues in certain models, and a few repairs involved

replacement of parts or having the solder joints re-flowed. Some persons chose

to take the unit apart and heated the graphic card to fix the connection failure.

And others had power capacitor issues; swollen capacitors are indicative of a

need to have them replaced; and the computer retested to be sure. Also, if the

iMac G5 is running hot, that can also appear as degraded video. The power

supplies may be dusty inside, so the computer may need to be cleaned. Any

thing you can do, should be viewed as part of a troubleshooting theme.

Good luck! 🙂

A large number of PowerBooks and G5 iMacs having serial numbers beginning with W8 had known bad displays installed. However, the fact that yours does not show the symptoms on safe boot may point to a less fatal issue. Do you have a way to connect an external monitor? Whether or not the stripes show on an external monitor after a normal boot would be a major troubleshooting help.

Well, that is definitely not the type of striping that shows with the known "W8" display defect. However, the fact that it shows in a screenshot usually points to bad graphics processor hardware and not the display panel itself. Why it does not show on safe boot has me baffled at this point.

If you can tell us the exact sub-model of the G5, I can try researching it more later today. Find System Profiler in your Utilities folder and launch it. The opening screen will look something like this:

The line I've indicated with the red arrow is the model code. Yours should read "PowerMacXX,X" where the X's are numbers. Please post that code along with your screen size measured diagonally (either 17 or 20 inches for the G5s).

Also, do you still have the original install/restore disks that were shipped with the computer?

Thanks. I looked at some repair sites and it appears your model does not have a removable set of video hardware--it's integral with the logic board. Therefore any replacement of the graphics hardware would require an entire logic board replacement.

To get back to the safe v. normal boot findings, is any system modifier present, like anti-virus or cleaning apps, memory checkers, etc installed? What about utilities that change the interface?

Without the original disks you can't run Apple Hardware Tests, but then they don't always pick up video issues anyway.

K Schaffer's mention of the insides being dirty and causing overheating is worth investigating. The fans in our computers inhale large volumes of air every day and the air around us has particulate matter. I'd first check the vents on the case bottom and clean them if they are dirty. Takeapart instructions or your model are here:

https://www.ifixit.com/Device/iMac_G5_17%22_Model_A1058

Opening the case back should let you see if the fans and airpaths are dirty without need for much further disassembly.

This is my Hardware Test: Video Ram -> Error Detected; ERROR CODE: 2ATI/1/4: 113-XXXXX-117

Well, there you go. That looks like a video hardware failure. That code is not in my list but the facts that the report states "Video RAM Error" and has the "ATI" initials are pretty definitive. "ATI"--that model iMac only shipped with an ATI 9600 video chipset according to the MacTracker database, so ATI in the report matches the video hardware brans in your computer.

Unless you can find a known-good logic board on the used/pulled market, you will have to live with the artifacts. Believe me, I've seen much worse. At this point yours are, based on what I see in your screenshots, more cosmetic. That may get worse with time however. At least the computer appears usable at this point.