Let me preface this by saying that I read the "Understanding Intel Mac RAM" guide, but it's either too vague or I'm just stupid (probably the latter), because I still don't fully get it. I plan on using the stock Apple RAM and a 4GB kit (don't think I need the power of the 8 kit just yet), probably from OWC. From what I've read, I think my particular configuration needs to be like this: Riser A 2GB | 2GB | empty | empty Riser B 1GB | 1GB | empty | empty With this, A1 and A2 are the same, as are B1 and B2. Is this a correct arrangement? Also, I get that full 256-bit access won't be available with this configuration. When the guide says there is a small speed benefit to doing this, just how small are we talking? Would it be worth it to just get four 2GB modules and stick the stock RAM in A3/A4? Thanks for your help, all.