Hi

I don't have a system to compare with the two RAM types so I couldn't say much about performance boosts between the 1333 and 1600 MHz RAM chipsets.  Since RAM is where your programs sit temporarily and act as a buffer between yourself and the Hard Drive then in my view the faster the better.

DDR3 doesn't refer to how many boards you have.  2 of one brand and 1 of the other shouldn't be an issue as long as they are matched in terms of speed and type.  I'm assuming Dell ran out of one brand so used the other (you might want to check that they haven't yanked an old one out of your old system or something similar.  I'm not sure of their replacement policy).

Yes, Tri-Channel ends up being faster because there is a whole extra lane over dual-channel.

If tri-channel isn't installed in matched sets of 3, it won't run tri-channel (if falls back to dual-channel).

As long as all 3 DIMMs are the same specs (but different brands) it should still, conceivably, make a matched set (but I have never tried it). Instead, I always buy and swap them in exact sets of 3 ... it's just more fool-proof that way. I've been doing that for a while now (even with dual-channel memory).

Not sure how you test it ... I think the BIOS or some 3rd party Windows utils might be able to tell if they are, indeed, running in Tri-Channel mode. 

Im kinda confused as to why they sell the Tri chaned ram in sets of 3 just as double chanel in sets of 2?. I would think their is a reason behind this. But I never was one to mix Ram as it is a vital and really can efect performance big time. I know someone who would just throw any ram in his PC and was wondering why the PC always fell short performance wize he broke down and got some decent ram and his machine ran like a new rig compared to how it ran previous. I don't know I guess it's just me but I never could understand ram I wish they had a ram guide to explain everything in terms that you don't have to be a guru to understand.

But thanks maybe someone else will have answers and have they  have upgraded themselves from 1333Mhz to 1600Mhz and can justify id the boost in performance is worth the higher cost . What about haveing 12 gigs instead of 6 do you think 12 is kinda overkill? Anyway I could not aford 12 gigs in the 1600 Mhz as its a huge jump in cost between the 2 gig sticks and the 4 gig sticks.

Even if I do upgrade I hear some horror storries of haveing to manually set settings if thats the case Im in trouble and will have to bring it to a computer repair shop as it's way over my head but then again many say they stick them in and it reconizes and adjust all the settings to where they are supposed to be. It's just a great computer and would like to have it running to it's full potential.

Thanks

jeffcmfrt66

With 12 gigs of DDR3-1333 in Tri-Channel mode ... you are in good shape.

With only 3 slots ... that would be 3x 4gb DDR3-1600 ... very expensive and not worth the slight performance increase IMHO.