can't get into computer - always wants to restart

can't get into computer - please help?

Specs:
PPC G5
2x2.5 GHz
OSX 10.4

The computer was working great for a while. Then all of a sudden, the screen greys out and displays a message asking me to restart (in several languages no less). When I restart, I can't even get to the finder before the same thing happens. Grey screen, need to restart. How do I fix this?!?!?

Thanks!

It's a kernel panic, and you're right to check the RAM as first likely cause. What combinations of RAM sticks did you try by "switching out" (you have spares?). Leaving it unplugged as a temporary solution suggests a PMU fault, possibly a failing PSU. Use Console to check its log for reported errors, also /Library/Logs >panic.log. I'm not a Mac technician, but use the Search of this forum for PMU and PSU remedies.

I had recently upgraded the RAM. I went from 2x256 + 2x 512 to 4x1Gb. So I had a total of 8 cards (or 4 pairs) to mix and match. It turns out that one of the 512s was bad. Regardless, I tried almost every combination with limited amounts of success. All had the same result though.

When you say "see Console to check its log for reported errors, also /Library/Logs >panic.log."

A) I am not exactly sure what you mean.
B) How can I do this when I can't get in in the first place?

Thanks for the help though!

oh oh, ok.
I found it.

there are several reports of Unresolved kernel traps. and a lot of hex codes everywhere. what am I looking for specifically?

Remove all the 256 and 512MB modules and see how that goes. Should not notice a great difference wih 4GB compared to 5.5GB and you can always add more matched pairs.