I have a 2009, octo-core, 2.26GHz Mac Pro (MacPro4,1). I bought it with 8GB of memory, which came with 4x2GB modules, two installed in each "side" of the machine. I'd like to bump this up to 16GB total. Looking at OWC, I can buy 4 2GB modules of 1066MHz ECC RAM for $145.99. I can also buy 2 4GB modules of 1066MHz ECC RAM for $146.99. So, I can pay one whole dollar more and get the 16GB I want with two extra slots for adding more memory in the future. This seems like the way to go except that I would then be running with 4x2GB and 2x4GB modules. Will that work? Will I take a performance hit? In what way should I install this in order to maximize bandwidth of the triple-channel memory controller? Thanks!