Hardware problem in PowerPC G5

My wife's PowerPC G5 won't power up. We had no power surges (it's also connected to a UPS) or any other indicators of anything going wrong. Specifically, the symptoms are as follows: I press the power button and I hear the fan kick in and power indicator light goes on. After a few moments, the indicator light starts flashing in groups of 3 flashes followed by a pause. After a number of minutes, the fan noise starts getting louder and louder. All the while, the monitor is totally dark (power light is on). At this point I turned off the computer. I also unplugged the machine for about 10 minutes and retried; no differences.

I downloaded a pdf file entitled "Power Mac G5 User's Guide" which explains (assuming the power light is that same indicator light) that 3 flashes means "incompatible RAM installed". Am I correct to assume that I may have bad memory (obviously I did not install any RAM)? If so, is there an easy way to validate which memory board is bad or should I replace them all? The G5 is about 4 years old, more or less.

Any pointers or advice would be appreciated. The good news is that the computer is completely backed up!! Thank you, Time Machine!!

Joe

In case anyone is curious, the problem was probably memory-related. I took the G5 to an Apple store where, of course, it booted up immediately. The technician opened the box, cleaned the insides and reseated the memory cards. The computer has been working fine ever since.