I have a first gen 2.66 Mac Pro with 10.5.5. I have had 3gb of RAM installed for over a year. Just recently I noiced system info shows I have only 2gb of RAM installed. It shows I have 4 slots of 512mb installed.. however 2 of those are 1gb each. It used to show 3gb but now recognizes my two 1gb sticks as 512mb. Here is a screen shot of system profiler www.statikcatstudio.com/ram.tiff I just opened my Mac and double checked the RAM. All 4 slots on the top board are full and slots 3/4 have 1gb Transcend RAM. These are Mac Pro compatible modules.. and like I said they used to work. So what would cause OSX to see 1gb as 512mb? Could the RAM be bad? Thanks in advance. Edit: I have been reading around online about Parallels causing some system issue of max RAM limits. I had parallels installed awhile ago and (tried) to remove it via Spring Cleaner. Maybe this is related?