I have a 1.6Ghz G5...I want to buy RAM for the machine and I know it takes PC3200 DDR 400. The stock 2X128 chips inside are PC2700 (DDR 333) though. Now I know there are high density chips and low density chips out there. What's the difference? I bought a pair of 512's before and I didn't check to see if they were high or low density.... i put them in and they worked fine. I bought 2X1Gb PC3200 and it would not register on my Mac. I took it to a friend who had PC and I put the chips into the Windows machine and windows didn't recognize the modules. Will high density chips register on the G5?