MP 2.8 RAM question

[select]

In these days i would to expand the RAM in my Mac Pro 2.8 (Early 2008).
Now i have 4GB (2x1GB Original + 2x1GB Kingston). I would buy another 2x2GB Kingston modules and bring it to 12GB (4x1GB + 4x2GB).
Can create delay with this size difference (i have to replace the 1GB modules) or you can install without problems?

Thank you

 

[Umbongo]

Yes you can have mixed modules. Put the 2x2GB in slot 1&2 on riser A and the 1GB modules all on riser B so each riser has 4GB of memory.