Have 3 x 2GB = 6GB, ok to add 4GB mem for 10GB?

[Luba]

I have a 2.66 Quad with 6GB of memory, I know if I fill the other slot I will lose triple channel memory access, but can I fill that last slot with a 4GB stick?

Any other downside of filling that last slot?

Am I better off selling the 3 x 2GB of memory and buying 2 x 4 GB of memory for 8 GB of memory and later buy the last stick of memory to bring it up to 12 GB (if needed)?

 

[DetroitRockCity]

I am bumping this, because I have the same exact question.
I have 6GB of ram in my Mac Pro. Would adding a 4GB module to the last slot decrease the performance or get rid of triple channel?

 

[Dr.Pants]

A reference found with Mroogle.

Yes, you can have that extra stick and have it run. It will just do it either in (not likely) dual or (likely) single channel. 2x2 + 2x4 would be a good in-between combination, since on i7 triple channel and dual channel have little difference.

@Luba - IMO, 2x4 now and then add a third DIMM later, followed by a fourth should you choose, if those are the only choices. I prefer my above solution.

@Detroit - Yes, going from triple-channel to single-channel will be a disappointment.