Different RAM in Different Triple Channel Banks!?

I don't think that mixing timings is a good idea. It could dumb your new ram down to the old ram levels. The same way crossfireing a 4890 and a 4870 makes 2 4870's. Remember that your mobo is optimized for 3 channels anyway and any more won't show you much improvement. Just try to sell the new stuff when you get it.