10 Replies Latest reply on Apr 16, 2010 7:01 AM by JoaoMOS

    Lost on which RAM for i7-930


      I'm building a new development machine (with Windows 7 64bit). I write database software and do quite a bit of work in Adobe products. So more RAM is preferable. But I'm reading so much confliciting info out there that I'm a little lost. I read that it's best to use multiples of 3 sticks. Is this true? But then somewhere else I read it doesn't see more than 3. Is this true? So if you want 12GB you have to use 3 @ 4GB. That's a bit pricey. I'd rather use 6 @ 2GB. The board I'm considering is the Asus P6X58D which has 6 slots. So the other question is regarding speed. I read that DDR3 - 1066 is all the i7 can really take advantage of so gooing to DDR 3 - 1600 is a waste of money. I know hardware to some degree but am far from an expert. I know enough to put a reliable machine together and have it last for a good long while. But I'm pushign the limit of my knowledge on this one. I always build my own machines successfully but this time around I'm a bit confused I guess. Looking for some good feedback on what to use with the board and cpu mentioned. I'm considering 2 sets of CORSAIR XMS3 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) to total 12GB. Not sure if that's wise or not. When I built my current machine, I made the mistake of buying 8GB of RAM only to find out later that Win XP 32 bit could only see around 3.5 GB. I don't want to make that same kind of mistake this time around. Thanks for any input.

        • 1. Re: Lost on which RAM for i7-930

          See your CPU soecifications at http://ark.intel.com/Product.aspx?id=41447

          See the memory limit adressing capabilities of diferent Windows 7versions http://msdn.microsoft.com/en-us/library/aa366778(VS.85).aspx

          Effectively I7 only supports DDR3 modules up to1066 MHZ but you can go up to 24 GB of adressable phisical memory or 6 DIMMs of 4 GB each.

          I don't know why I7 doesn't adress both ranks of slots. Probablly what you have heard is that iy only works with at least 2 slots of at least one rank filled or that you must have the same type and capacity of memory modules in each rank. If you have two DIMMs you will work in dual chanel. I f you have 3 you work with 3 channel.For the moment you will not be aware to use your 12GB (3x6x2 DIMMs of 2GB). But with the evolution of software to 64 bits and to multi core use I think briefly you will, with the kind of applications you work, be able to use even 24 GB.

          Be aware of the limitations of the Windows version you use.

          • 2. Re: Lost on which RAM for i7-930

            Thanks. And yes, aware of the Win7 limitations. That's not a problem. But from reading the page on the i7-930 limitations it sounds like regardless of software being run using 6 sticks And/Or anything higher than DDR3-1066 is a complete waste of money. Am I understanding that correctly? So using 3 sticks at 4 GB each would work for 12GB total but still have to stay at 1066 or less. Is that right too? Okay, so all of the i7's say triple, even the i7 extremes. They don't recognize that second bank of channels at all? So the boards that have 6 slots for RAM are just teasing us or trickign us in to spending more on RAM or just getting ready for the next generation of CPU's? So it sounds like at this point the best thing to do (ignoring cost) is to get 3 sticks at the highest GB available at 1066 but lowest latency to get the most benefit?

            • 3. Re: Lost on which RAM for i7-930

              You didn’t understand me. It’s normal because I’m not a natural English speaker.

              I correct. I don’t see why I7 doesn’t address both ranks of DIMMs. Of course all I7 processors must recognize and read the second rank of DIMMs. But not all I7 processors have 3 channels to access memory. Only 9 series, I think. If you want 12GB of RAM memory you can use 6 DIMM’s of 2 GB each, or, if you think to expand in the future to 24GB, you can only fill one rank with 3 DIMMs of 4GB. I think that those DIMMs are yet too expensive and not all the manufacturers are providing them.

              I have an I7 920 with 6 GB of RAM memory (3x2GB DIMMs) and I never saw more than 50% of memory used. Only with the OS and its processes working, about 2GB of RAM are used. I don’t know yet why, but I give responsibility to the actual software. I work too with ADOBE applications, and even with PHOTOSHOP CS4 64 bits I don’t see more memory used. Even with several ADOBE applications working and with heavy documents. And even the processor is only used at 17%. But I hope that in a short period we will need to use the top capacity of the CPU and RAM

              See in this forum, some few lines after your post, the question posted by petesieber and which I am following.

              • 4. Re: Lost on which RAM for i7-930

                Okay, when you say "I don’t see why I7 doesn’t address both ranks of  DIMMs." do you mean "There's no reason that i7 should not be able to address both ranks of  DIMMs." meaning that in your opinion an i7 will see all 6 slots (for series 900)?


                And yes, the 4GB sticks are quite expensive especially for CAS 7 and such. 2GB are much cheaper. So it's way more economical to go with 6x2 instead of 4x3. That's my predicament. I don't want to spend the $ on 4's. Anyway, every time I've ever upgraded to more RAM I've always had to buy all new anyway so that it all matches. I had 2x1GB in my current machine and when I went to 4 I tried adding just 2 more 1GB but it didn't work. I had to toss the 1GBs and get 2 new 2GBs. So I figure that's just the way it is. Always end up gettign all new if you wait more than a year or so to upgrade. I don't expect to ever need 24GB but 12 could come in handy IMO. SQL is a RAM hog adn even though I'm just a developer and not runnign a live system, when I do dev work, my RAM gets eaten up by SQL.

                • 5. Re: Lost on which RAM for i7-930

                  Well I think I've decided to go with one of these (2 sets for a total of 12GB):


                  CORSAIR DOMINATOR 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Triple Channel Kit Desktop Memory Model TR3X6G1600C8D (http://www.newegg.com/Product/Product.aspx?Item=N82E16820145224)

                  (timing is 8-8-8-24) and can get locally for around $250/set (only thing that concerns me here is the higher timing and the very tall heat spreader possibly interfering with the CPU heatsink).




                  CORSAIR XMS3 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model TR3X6G1600C7 G (http://www.newegg.com/Product/Product.aspx?Item=N82E16820145242)

                  (timing is 7-7-7-20) and can only get online for $260/set




                  Corsair XMS 6GB (3x2GB) DDR3-1600 (PC3-12800) RAM (mfr # CMX6GX3M3C1600C) (http://www.microcenter.com/single_product_results.phtml?product_id=0328198)

                  (timing is 7-8-7-20) and can only get locally for $200/set


                  I prefer to get RAM locally in case there's a problem and I have to exchange it (same with CPU and mobo). So I'm leaning toward the first and third one above. But the 2nd one has lower timing so I'd kind of like to go that route but I'm betting that I'm not going to notice a difference. I'm guessing I wouldn't notice a difference with any of the above. Is that a good guess? Any input from anyone on this?


                  Also, is there any difference between getting "3 sets of 2 sticks @ 2GB each"  AND  "2 sets of 3 sticks @ 2GB each"? I read somewhere that it's best to get 3 sticks in a kit for the i7 because they're matched.

                  • 6. Re: Lost on which RAM for i7-930

                    Well, you insist in 1600 MHz DDR3 SDRAM Modules.

                    Be careful. You must follow the specifications of the CPU manufacturer. And those modules are not recomended. Maximum of 1060 MHz. This means that maybe the memory controller is not prepared for the transfer rate you are providing or for the electrical demands of such modules. I send you a link to the Elpida datashhet of DDR3  1600, 1333 and 1066 MHz.


                    In page 16 you can find the times of access to the SDRAM Dies who compose the modules. tCK means yhe number of clocks between diferent operations. I have some dificulty of explaining that to you know. That demands a deep knowledge of the way an SDRAM Die works. But you can see for instance that tRC, which means active to active row latency, the latency is lower in 1060 than in 1600. And why? Because the time you must wait is measured in nanoseconds, and in that aspect, the difference between all the frequencies is none. And that latency is of 25 ns, or about 100 CPU clock cicles.  When you have an active row, you read normally through bursts which go from 2 to 8 or full page. But even there you have latencies to respect. The bigger the burst, the bigger the diference you will have between the diferent frequencies of memory. But to the transfer rate time you musts add latency So, the diffrence is not so liquid like it seems at firs look. Latency is the time necessary for the different circuistts to equilibrate, for the reading of the charge inside the capacitor through sense amplifiers, and so on. And those are equal.

                    And look at page 15 and see the difference in mA between the diferent memories in all its operations. Is the CPU prepared to furnish that amount of mA. Or will that create a conflict? I really don't know. But Intel says maximum 1066 MHz.

                    About the kits. What is shure is that all the modules in the same rank (3) must be equal. They are accessed in parallel and it is expected that they accomplish their opperations at exactly the same time. The kits of 2 are probably for dual chanel memories. Look! DDR2 and DDR3 have nothing to do with ter number of channels. Only with improvements that allow lowest voltages and in consequence bigger frequencies.

                    For me, the most important in a system its the equilibrium between all the components. CPU, main memory, cache dimension and politics, comunication between all components. In that aspect I think I7 series 9 is a vanguard CPU chip. For these memories there is not latency, And the accesses are of about one or two CPU clock cicles for each level. Independent comunication between memory and other components. FSB substituted by Quick Path Interconnect (not only allowing a lot bigger transfer rate but discharged of comunication with memory). Quad Core, with really independent policies. 2 Cache level 1 of  32 KB for each one. 1 Cache level 2 of 256 MB for each one. 1 Cache level 3 of 8 MB for all. And all this in the same chip. Do you know that cache occupies almost 1/3 of Chip area. And with so much cache, long cache blocks allowed by 3 chanel memory, you will have a cache hit above 95% shurelly.

                    I think you have a good processor. Why to worry so much with memory frequency? I would worry with the evolution of software and with the efficiency of Operating Systems on working with such a deal of ressources. Till the moment I didn't see my CPU used above 17% and my 6 GB RAM memory above 50%, even with two browsers, all Office 2010 applications and all ADOBE applications working togheter in a mutiprocessing environement. And under Windows 7 64 bits. Why so low use of CPU? Maybe only one CORE is being used. And Why?

                    Look. I myself would follow Intel specifications. You have memory DIMMs datasheets which you can consult in Micron, Samsung, Kingston, and lots of others.

                    • 7. Re: Lost on which RAM for i7-930

                      Thanks. I appreciate your very thorough response. Everything you said makes sense and I do understand much of it. My big question now is why is there so much DDR3 RAM out there that's well over 1066?


                      In fact, on the microcenter website, there's only 1 offering of DDR3 1066 while there are 7 DDR3 1333s, 17 DDR3 1600s and 3 DDR3 2000s. At Newegg there are only 6 at 1066. And in almost all the reviews people talk about improved performance from whatever they were using before when they use higher RAM speeds with the various i7 chips.


                      It could be extrapolated from what you are saying that higher speed RAM is just a way for the RAM makers to make more money off of saps that beleive they're getting somethign that the CPU can't even use and that the people saying they are getting great results are just seeing the results of other system changes and that they have nothing to do with the higher speed RAM and that in fact if they used 1066 instead of 1600 they'd see the same results.


                      Don't get me wrong, I'm not disputing what you are saying, I'm just trying to understand the masses of conflicting information out there.


                      And then there's the question of OC. Is overclocking RAM above 1066 the same thing as using higher base speed RAM?


                      Lastly I found this: http://www.intel.com/en_US/Assets/PDF/prodspec/XMPself-certwebposting_corei7.pdf. I know it's for the i7 extreme but on the other i7 extreme page that you referenced in your first post to this thread it also says 1066 just like all the other i7's. And this page for the other i7s: http://www.intel.com/en_US/Assets/PDF/prodspec/ww06-10-XMP-corei7.pdf

                      • 8. Re: Lost on which RAM for i7-930

                        Please don't misenderstand me. I didn't mean anything like that. I only tried to explain you why I thought  in your case, that difference, which obviously exists, was not so important like other factors. You answered too quickly to have read and understood all what I said. Really, I shouldn't, beacuse it's really very confuse the technical  way a SDRAM works. Sorry.

                        Off course, a 1600 data transfer rate is obviously greater than a 1060 one. I just don't understand why Intel, with a top processor like I7 specifies the 1060 transfer rate like the maximum one for it. Did you allready put that question to yourself, in a deep way?

                        • 9. Re: Lost on which RAM for i7-930

                          I sugest you to read some pages ofe the following link, to know something more about your CPU