Power Mac G5 only powers up in safe mode green and pink distortion in square patterns on monitor

Hello Mike,

Classic symptoms of a failed Video card, but try pulling it, cleaning the contacts, & reseating it.

Might be time to replace the PRAM Battery, 4 years is close to their lifespan, far less if ever without AC power, & can cause strange startup problems...

See which one your G5 has...

http://eshop.macsales.com/item/Newer%20Technology/CR2032/

http://eshop.macsales.com/item/Newer%20Technology/BAA36VPRAM/

Cleaning the contacts and reseating is definitely the first step.

Use an eraser, lightly rub the gold contacts, then wipe with a clean, soft cloth.

If one has it, using PCB (electrical board and contact) spray cleaner is even better.

After cleaning, reinstall the card paying attention to proper seating and tightening of the hold down screw.

If the card has a fan, insure that the fan is turning. If not, disassemble, clean, lubricate and reassemble.

Below are links to my articles on the topic:

16196A0F-952B-47ED-A9F9-91F7B0ECA431.html

C874D84E-96DD-4DFF-9566-7C66BE065BB5.html

AF6A8D44-7864-4F5A-A45A-DB56A8663B45.html

The fan may also possibly be replaced.

If card replacement is opted for, now or later, search eBay for one of the following:

4B4B7BA2-7ABB-47F1-87AC-B03D37942BEE.html

Yes if the battery was dead it would cause that, and likely is after long storage. What monitor are you using? The original that sat in storage with the computer? Video cards seldom fail, monitors tend to more. The first thing I do with video failure is swap out the monitor, to see if the computer works on another monitor. Every computer shop does that, to determine the monitor 1st, then driver, then display adapter. Jmac has giving great advice to try.

One other possibility, and it could occur while in storage, is the failure of or degradation of a capacitor and/or it's quality.

A failed, damaged, swollen or even broken capacitor can cause a row or two (or more) of geometrically arranged graphic anomalies (kind of like you diagramed), typically running the entire height of a screen (desk top). Color variables are also common in said conditions.

I have seen this more than I care to with purchase of used PC cards on eBay and such....

If your card is a Radeon card, look at the things that look like tin cans on the board.

If any are swollen (tops not flat) or loose, the failure point is likely there.

Replacement of a bad capacitor or reconnection with solder is possible, but not for everyone.

A replacement card is needed if the issue is capacitor related and repair isn't an option.

So if that battery is dead then wouldn't the time be wrong everytime I turn on the computer?

If Sys Prefs are set to update Date/Time from the internet, then those would be correct before you could check it.

You can disconnect from the Internet, or turn off that function & reboot to test it.