optimum 8 core RAM dimm configuration

Hi,

I've been looking around on the net all day and I've found a lot of info but nothing specific enough, so I thought I'd ask here.

I've got a 2.4 8-core 2010 mac pro with 8 dimm slots. It came with 6 x 1gb dimm chips. I just bought 4 x 4gb kingston chips.

At the moment I've put them in two sets of 2x4gb then 2x1gb for each socket to get 20gb.

Some sources say this is a good setup, another source says that the best would be four sets of 1x4gb then 1x1gb. My instinct says for the best performance I should just use two sets of 2x4gb and ditch the 1gb chips completely...

I'm using my computer for a lot of after effects and cinema 4d. Is it possible for me to have optimum performance and 20gb of ram with these chips or will putting the 1gb chips in always reduce performance?

thanks