The ram is the constaint if you don't change the speed ratio for the memory vs the bus speed. Most motherboards will let you do that though. If were me and I really had to choose between the two, for rendering speed I would go with the fast CPU. The only reason you might want that much RAM in my opinion is to enable long RAM previews for viewing smooth playback with lots of effects.

Thanks for your replies.

"apparently it won't overclock by more than 100-200MHz with 16GB"

No I'm not Bob, which is why I was careful to use the word "apparently" in the hope that someone might challenge it, as I'm pleased to see you and srode are doing.

This is what the suppliers (scan.co.uk if anayone is interested) say (as you acn see I got it a bit wrongin my earlier post, in fact they're suggesting 200-400MHz o/c)

In regards to the overclocking, we can overclock if you went for 8 Gb of RAM in a 2 x 4 Gb configuration, but if you went for 16 Gb in a 4 x 4 Gb RAM configuration, this will cause the overclock to be limited to about 200-400 Mhz above the stock speed. The reasons for this are if you populate all the memory banks on a motherboard, the additional strain placed on the memory controller inhibits any overclocking.

One of the reasons I was concerned about limiting the system to 8GB RAM is that I seem to recall (though I cannot find the threads now) people having problems with "media offline" & red events on the timeline in Vegas 9.0 64bit, back when the i7 920s came out and there seemed to be some sort of concensus that it really needed 12GB RAM to perform properly.

But this hasn't been mentioned here so I' m guessing one of:
a) It was a Vegas problem which has been resolved
b) 12GB is only relevant to triple channel architecture, 8GB is fine for dual
c) I imagined I'd read this and/or it was nothing to do with the amount of RAM

I haven't worked with a 16gb RAM set up or an I7 and I can't speak from personal experience on that set up - my understanding is on paper you should be able to but I would guess the folks you are working with have tried and failed, and so their experience is what I would go by. I doubt they have overlooked the obvious in tuning the board to OC with 16gb. If it were me, and I had to choose I would go for the faster clock speed and not the additional RAM. It really depends on what you are looking for, fast render or long RAM previews in my opinion. I don't think 6 or 8 gb will set you up for limitations on usability of Vegas other than shorter RAM previews which is not particularly critical IMHO.

Pretty certain you can now get RAM in 8GB per stick so you could get 16GB without fully populating the board.

Certainly if you want a lot of RAM then you need to go to registered RAM and the new SB CPUs that'll support that will not be released for a few months and use a different socket (2011).

My understanding though is that the memory buss clock and the CPU clock on the K series CPUs are unlocked if you're using the P67 mobos. Then again I'm no expert and a lot of suppliers might not be upto speed on these new CPUs either. A really good place to get the latest updates if from one of the overclockers fora.

Our local one (http://forums.overclockers.com.au/?) has some very well clued up people on it....and as you might expect some not so smart people as well but you soon get to know whose who.

Bob.

Just to clear things up. Sandybridge is overclocked by changing the multiplier on the CPU, NOT by increasing buss speed as was the case previously.

So, overclocking the Sandybridge cpu has NO EFFECT on memory stability. You can just leave the memory at the default 1333, or you can overclock it independently from the CPU for a little extra performance. If you do go with 16GB generally it will overclock a little less than 4 or 8GB.

So don't base your purchase decision on the amount of memory you require. If you are doing a lot of video work you might want to consider the 2600k as you get hyperthreading, 2MB extra cache, 100Mhz more stock speed, and the possibility that Intel bins the "best" chips for the 2600k. Which could lead to a better (more stable and faster) overclock. From what I have been reading unless you get a really cherry chip and go with water cooling, for a good safe, stable overclock you should probably stay at in the 4.3 to 4.5GHz range.

- Mark