Memory Timing Questions - Memory size limits Q's

[RobAGD]

OK I am have a Dell Persision M6600 with the i7-2860 and 4 dimm slots

I ordered this with 4gb of memory knowing I was going to stuff 32gb in when I got the chance.

Now oddly enough from Dell they mention I can run 16gb of 1600 or 32gb of 1333

Up to 16GB6 DDR3 SDRAM at 1600Mhz - 4 DIMMS
Up to 32GB6 DDR3 SDRAM at 1333Mhz - 4 DIMMS

and its using the Mobile Intel® QM67 Express chipset.

To be truthful it has been way to long for me in building systems, I have been on laptops for the last 10 years+ but I would assume that the QM67 chip set won't allow for the 32gb of 1600 which seems kinda odd as it will at least handle 16gb at that speed.

So I am just kind of wondering why from a technical standpoint ( and my general curiosity )


So next up is, I am picking up the memory. I was looking at Crucial http://www.crucial.com/store/mpartspecs.aspx?mtbpoid=4B22B2EEA5CA7304

and started poking around on new egg and was looking at :

G. Skill - http://www.newegg.com/Product/Product.aspx?Item=N82E16820231582

Corsair Vengeance - http://www.newegg.com/Product/Product.aspx?Item=N82E16820233265

Now this is a work box, no OC'ing. I use it for video editing, etc with some Starcraft II thrown in. The thing I am seeing is a difference in the CAS timing 11-11-11 vs 10-10-10 and while I know 10 is "faster" than 11 is there really an appreciable difference ?

Given there isn't much cost difference between these kits I was just kind of wondering.

Thanks for your insight

-Robert

 

[Formula.350]

Whether or not Dell has some BIOS coding block in place to keep you from selecting 1600MHz when over X-amount of RAM is being used, I don't know, but the likelihood of the system not being able to run it at that speed is pretty good. There are reasons beyond my explainable knowledge for what could keep it from running properly, but most of the time it's just a specification Intel/AMD/motherboard maker have implemented to insure stability across all systems. Like AMD's Phenom II memory controller was only specced for DDR3-1333, but I doubt anyone actually ran into an instance where DDR3-1600 memory could run at 1600 on a PhII chip.

SO, if the setting is present in the BIOS with all that memory installed, it'll probably run at that speed just fine.

As far as those kits go, you need to keep in mind that the G.Skill and Corsair kits both are rated at 1.5V, and the Crucial is 1.35V which ill be a better overall pick. There are many reasons for that, but given it's a laptop the primary one would be lower heat and less power consumption (not that memory really consumes much). Matter of fact, on NewEgg only the Crucial and Mushkin kits are 1.35V, everything else is 1.5V...

If people determine 1.5V not to be a problem for an Intel mobile chip, then there is GeIL 2x8GB DDR3-1600 kit at 10-10-10 for $72...
http://www.newegg.com/Product/Product.aspx?Item=N82E16820144593
But as for any discernible speed difference, I can't say how it effects Intel chips, but I'm always one who says "Why not?" if it's available, specially given there is no price premium attached heh If you're running Intel's IGP, then I'd probably go with the CAS10 kits.

Hope that helps some

 

[Cheetoz]

To be truthful it has been way to long for me in building systems, I have been on laptops for the last 10 years+ but I would assume that the QM67 chip set won't allow for the 32gb of 1600 which seems kinda odd as it will at least handle 16gb at that speed.

So I am just kind of wondering why from a technical standpoint ( and my general curiosity )

If I were to guess, I would say because of the snoopy cache coherence protocol that is used. The chip is able to snoop the bus for the two sticks of memory at the higher 1600 bandwidth, but would not be fast enough to snoop the bus with more memory using the same bandwidth.