My trusty old G5 DP, which funtioned flawlessly for 5 years with 8 1GB sticks of RAM, but currently relegated to file server tasks, recently choked on a system update. In reinstalling the system I discovered that it was only seeing 7.5 GB of RAM, seeing 2 of the 1 GB sticks as 512 MB. I removed the RAM, did some minor cleaning, then replaced it and rebooted. The relatively luxurious 7.5 GB was now being seen as 3 GB. Removed and reseated all of the RAM again, now it's only showing up as 2 GB, showing 4 of the slots empty and the RAM it sees is showing up as 512 MB. Any thoughts?