Imac g5 is having weird screen problems, how do i fix this, what could be wrong?

It does it with mac os 10.4

here is a picture that i took

http://i199.photobucket.com/albums/aa28/rei_wilder/Picture1.png

This imac is running a 500 gb hd, it was missing the hd when i got it, has 1gb of ram, could be 3rd party, and th os was installed from a burnt iso image, since it did not have the discs, could this be caused by a bad iso image, or is it the logic board, or perhaps the video gpu?

Email me at chakanevil at gmail dot com

Could be a graphics problem, but since you loaded a pirated copy of Tiger on it you're not going to get any help from here.