Q: What does error code 2nyd/1/4:2103 indicate

Have you tried safe boot?

Something appears to be wrong with your video chip.  Video chips are solderd onto the logic board. 

Here is a workaround...

You may have a problem with the video chip.

Here is how to tell...

   Shutdown your machine.  Hold down the shift key.  Poweron.  Bootup will be longer.

     Wait awhile while you harddrive is being checked.

   An article on how to boot into safe mode.

     http://support.apple.com/kb/ht1455

Runs OK in safe mode...

Running in Safe mode leaves out some video drivers.  Which results in your machine not using advanced video hardware. As luck would have it, you can run the safe mode video drivers in normal mode. 

Here is how:

https://discussions.apple.com/message/16057567#16057567

Look through the above thread.  See the second page.  You don't have to read through the first page.  Just go to the part where I try a solution that works.

Using the safe mode video driver results in these limitiations:

   -- OpenGL acceleration is not supported on this mac

   -- Your mac lacks quartz extreme acceleration

Summary of G5 problems. Includes instructions on a hardware fix for the brave at heart:

See -Rotten Apple- articles in both of these threads.

https://discussions.apple.com/thread/4023152?tstart=0

https://discussions.apple.com/message/18700825#18700825

Robert

No, you have a hardware problem

check out capacitors.

Your going to have to play around with the hardware alot to make progress.

You need to remove all attached devices to machine. will boot without keyboard & mouse.  Try different keyboard & mouse. Read an article that bad keyboard cased non boot.  very rare.  Once you try, go back to keyboard & mouse. 

Be sure to remove the ethernet cable.

Remove memory sticks.  Just let one stick in the machine.  Or the minimum if you need more than one.  Swap around with fingers crossed. Hope for the best. 

Always try booting in safe mode or from dvd.  Safe mode should  avoid the video issue.

The startup manager will list all of your bootable partitions then give you a choice of which to boot.  Hold down the option key then power on. This brings up the startup manager. Click on your hd. Click on right arrow key.

See this discussion...  Might be harddrive.

https://discussions.apple.com/thread/1428295?tstart=0

detach hd.  boot from dvd.

--------------------------------------------------------------

G5 has these hardware issues:

  -- bad capacitors on logic board

  -- bad capacitors in power supply

  -- badly soldered video chip

  -- "There were several Mac models with flat panel displays that had bad displays.

      Most had serial numbers beginning with "W8"---the code for one specific factory.

      This affected PowerBooks as well. If that's the case, the rest of the computer

      is probably fine." by Allan Jones in

     https://discussions.apple.com/message/21630224#21630224

Google: g5 capacitor replacement kit

More info on capacitor replacement kits

http://jimwarholic.com/2008/07/how-to-repair-apple-imac-g5.php

http://thecapking.com/applg5.html

A success story:

https://discussions.apple.com/message/22751906#22751906

Certainally. I believe so.  That's the problem.

A lot of people have reported success replacing the capacitors.

Robert

The startup manager will list all of your bootable partitions then give you a choice of which to boot.  Hold down the option key then power on. Continue holding down the option key until you see the startup manager. This brings up the startup manager. Click on your hd or disc. Click on right arrow key.

Still won't boot so re-installed OS X from original disks ( Panther 10.3.5)and system boots fine.

Where did you install Panther? Use startup manager to see your list of OS.

The previous system (Leopard 10.5.8) was saved to HD.

What do you mean by this?  Copies of the dvds?  Not sure this are installable. 

Can the original system be retrieved and, is so, is there a "file" that tells the computer where/when to boot and, if so, could I swap them between the two versions?

What's the original system?  Panther.  Leopard?

In this time frame, all OS software came on cd/dvd.  There was no hidden backup partition.

--------------------------------------------------------------

Restore Tiger 10.4 & Leopard 10.5  DVDs are available from Apple by calling 800-767-2775 as of January 20, 2013. Have your serial number ready. Have your credit card ready too.  There is a small fee.

https://discussions.apple.com/thread/4720126?tstart=0

which time the previous non-bootable installation of Leopard (10.5.8) was saved on the same HD in a file called "Previous Systems."

I do not know how to boot from this folder.

Give Apple another call.  See if you can talk them out of Leopard. See the end of my last post.

Otherwise you will have to find leopard on ebay.  Make sure you get the full retail version.  They are in black.  They grey disc are machine specific and only boot on the intended machine.

Robert

This is amazing!  When Tiger was released, it shipped only on DVD.  To  get the 4 cds, you had to send to Apple your DVD and $20.

What are you looking to do?  You would install the new system the same way as you did Panther. 

Do you have a lot of apps you would want to save? You should backup your entire hd to an external hd.

Be sure to get an old version of these utilities.  Drag & drop will copy all the data, but the result will not be bootable.

Here are two utilities for making a complete backup of your internal hard drive.  I've recommend using one of these so that you can create a bootable system  on your external hard drive. ( PPC require a firewire connected drive. )  Once created, you can run your system from the external drive.  Hold down the option key on your keyboard then power on your machine.  This will bring you in startup manager click on the drive image you wish to boot then click on the arrow key to the right.

"Clone, synchronize, backup. Schedule and forget it."

http://www.bombich.com/software/ccc.html

"SuperDuper is the wildly acclaimed program that makes recovery painless, because it makes creating a fully bootable backup painless."

http://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html

You need an external Firewire drive to boot a PowerPC Mac computer [ a few G5's will boot from USB ]. 

I recommend you do a google search on any external harddrive you are looking at.

I bought a low cost external drive enclosure. When I started having trouble with it, I did a google search and found a lot of complaints about the drive enclosure. I ended up buying a new drive enclosure. On my second go around, I decided to buy a drive enclosure with a good history of working with Macs. The chip set seems to be the key ingredient. The Oxford line of chips seems to be good. I got the Oxford 911.

I'd give OWC a call. 1-815-338-8685.

FireWire 800 + USB 3, + eSATA

&

save a little money interface:

FireWire 400 + USB 2.0

This web page lists both external harddrive types. You may need to scroll to the right to see both.

http://eshop.macsales.com/shop/firewire/1394/USB/EliteAL/eSATA_FW800_FW400_USB

     (2) FireWire 800/400 Ports (Up to 100MB/s / 50MB/s)

     (1) USB 3.0 Port (Up to 500MB/s / 60MB/s)

     (1) eSATA Port (Up to 300MB/s)

Has a combo firewire 800/400 port.  Not sure what this is.  Looks like you will  need 400 cable.

http://eshop.macsales.com/shop/ministack