FB-DIMM's and memory config

[Carlis]

Im looking at a mac pro. Apparantly 4 pieces of RAM is needed to utilize all four ram-chanels.
Question: Will I loose anything by mixing different RAM sizes like 2x512mb+2x1gb?

/Carlis

 

[Lord Evermore]

It's not totally clear. They show that each pair must be the same, which makes sense if each pair constitutes 2 channels, and operates in dual-channel mode. However in order to have a quad-channel 256-bit interface, all the modules would have to be matching.

I don't see anything on their site detailing exactly how the channels are laid out relative to the slots on each of the risers, so I don't even know how you'd install 4 modules in order to get quad channel.

 

[Talcite]

the ram is configured in dual channel mode minimum or something. I saw a pic of it inside. I would imagine you need four identical pieces for uad channel. You probably won't lose ram, but it might not be as fast. You can take up to 16 gigs of ram anyways.