It to me shows little benefit unless using programs like AutoCAD, CS5, etc., which can benefit from additional RAM. As for going with 6GB (3x2GB) at DDR3 1600 and adding 12GB (3x4GB) at DDR3 1333, I would not recommend mixing of RAM speeds (timings possibly too) and sizes! By mixing, you are increasing the likelihood of compatibility issues (speed, timings & voltage) and increased BSOD! In addition, adding more memory will have little to no effect on boot times, as that is more driven by the hard drive. The best way to increase boot times is to go with a SSD for your boot drive.
Agreed with tecmo43! Don't mix..... you are just asking for trouble. Ram (IMHO) is already a tricky area when it comes to voltages, timings etc. I've tried this on older systems and depending on how flexible your board is, it may not even recognize that you are using 4gb DIMMs instead of 2 so in that case you would be wasting your money.
If you are looking for VERY fast boot ups then SSD in RAID config would be best.... (SATA3 would be required). check out the OCZ Revo 2.....this thing is beast and will take up 1 PCI-E slot.
I was afraid of this. The motherboard is a P6X58D-E, which is quite new, so I'm thinking it won't matter, but I don't know for sure. The cpu is an i7.
I do a lot of work in 3d modeling and a ram upgrade is always appreciated. With 18 gigs, the sky is the limit.
What if I was to buy ram that has the same voltage as the current set?
I'm reluctant to ditch the current 6 gig set as I paid $170 for it when it came out. If I was forced to downclock to 1333Mhz, I'd be fine with that. As Tom's said... ram speed at triple channel doesn't affect much.
... yet, currently my triple channel 1600Mhz Gskill set is rated 7.5 by WEI - making it my "bottleneck"...