[heiesuke_oda]

I just bought 2 GB of Crucial RAM from Newegg Newegg.com - Crucial 512MB DDR2 667 (PC2 5300) ECC Fully Buffered Memory for Apple Server & Mac Pro Model CT6472AP667 - Retail. I got the 512s cuz I only want 4 GB max on my machine as i have read that its the proverbial limit of usefulness. I want to know how i should pair up the RAM modules. Thanx in advance.

[mduell]

With 6 modules of equal size, put 4 on one card and 2 on the other (in the slots closest to the logic board).
Since the 2 Apple modules are already on one card, you could just put all 4 Crucial modules on the other card and save yourself the hassle of pulling the first card out.

If it's not too late to cancel your order, you may want to reconsider and buy 2x1GB instead. The 2 slots further from the logic board have higher latency, adding to the already high latency of the FB-DIMMs in the Mac Pro.

[drpepper]

Go to OWC: Apple Mac G4 upgrades, Laptop Batteries, Memory, Drives and watch the installation video. That will make things crystal clear.

Tech Center at OtherWorldComputing.com

[SMacSteve]

If you do this you'll be missing out on the 256bit memory addressing capablities of the MacPro. If you follow Apple instructions on this you'll be putting the first two chips on the top (where they came installed) and the next two on the bottom directly below. The diagram on the inside of your panel door will clairify this.

Hope this helps.

[mduell]

Originally Posted by SMacSteve 

If you do this you'll be missing out on the 256bit memory addressing capablities of the MacPro. If you follow Apple instructions on this you'll be putting the first two chips on the top (where they came installed) and the next two on the bottom directly below. The diagram on the inside of your panel door will clairify this.

He bought 2GB in 512s, and he already has a pair of 512s stock, so he has 6 modules. There's no way to have 6 modules and not have a 256-bit (quad-channel) memory bus in the Mac Pro.