Hey everyone--I just got my G5 1.8ghz. It's great so far, however I've come across a strange problem: Prior to receiving the G5, I bought some more memory for it. At first I decided on a total of 1gb of RAM, so I bought two sticks of 256mb Corsair memory. A couple weeks later, I decided I wanted to go for a total of 1.5gb instead, so I ordered *another* two sticks of 256mb--same brand, same model of RAM. (Yes, I know, "why didn't you just get two sticks of 512mb to begin with?") So tonight I go to install my memory. Including the 512mb Apple gave with the computer, I've got 6 sticks of RAM in there. I turn on the computer, boot it up, and find that the computer is only seeing 1gb of RAM. I pulled out the chips, reseated them, even tried changing around which banks they were each installed in. I discovered that out of the four sticks of Corsair RAM I bought, only two of them work in the G5. The other two don't work, no matter where I put them. I took both sets out and compared them. The two pairs have different batch numbers on them, the labels are slightly different, but physically they look pretty much the same. Why do you think that one set will work but one set won't? Another weird thing I noticed is in the System Profiler. The system realizes that there is memory in there, but it still says "empty." If you look at System Profiler, there are three columns for the memory detail: Location, Type, and Size. For the locations where the 'bad' memory is, the type is listed as "DDR SDRAM." It sees that it is in there; if it didn't, that space would be blank. And for size, it just says "empty." So, what System Profiler is telling me is that I've got DDR SDRAM in these two slots, but they're empty. Huh? Any clues as to what is going on here?