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#11
I can tell you it will depend according to the chart in the manual as to which mode will be set depending which slots you insert the dimms into. That is what sets the mode. You will either see 3gb in dual or 3gb in triple according to that.
I think you'd have 6GB of RAM, in triple channel mode.
There's a chance that the motherboard may not like having all 6 slots populated, but you can probably address that by manually setting the RAM timings and voltages. (I had to do that on my Asus P6T Deluxe, to get six DIMMs to run at DDR3 1600. Probably not an issue at lower frequencies.)
Interesting! Here all four dimm slots are populated on this model for the 8gb presently installed without any issues once the memory with the manual listed voltage not the memory support list memory was in.
As long as the multiple dimms match you shouldn't run into any real problems if you follow the manual. You want the same voltage range to see the default memory speed. That requires bringing up the memory clock if the memory speed is higher then the default which is found typically at the slowest speed supported by the board.
Once you see the "ungauged" at post with the memory running at it's own native speed you're all set that way.