G.SKill 16Gb Problem

11. Just add more DRAM, it will be perfectly fine.
This is another one where you should turn and run or simply ignore the source, to paraphrase Dorothy’s famous line in the Wizard of Oz, “Toto, I don’t think we are in Kansas anymore”, I’d say “We aren’t working with DDR2 anymore”; or even “we aren’t working with early DDR3 anymore”. Starting about the same time the DRAM manufacturers decided to exceed the JEDEC DDR3 spec of 1600 being the max DRAM data rate that had ‘set’ standards (and even a little before when they started tightening up 1600 sticks, mixing sticks has not been as easy as it was with DDR and DDR2.
Simply put, mixing DRAM from different packages is a crapshoot (even when you have two identical packages of the same exact model of DRAM), maybe they will play nice or maybe they won’t. (I will add those that don’t appear to want to play can often be helped into playing nice with voltage and/or timing adjustments…but not always – there are no guarantees. A couple of examples of that are shown in my article “Not Just another DAMN DRAM Review (insert link) where two of the companies didn’t make 32GB sets of 2400 DRAM and sent me a pair of matching 2x8GB sets. Neither worked initially and took minor adjustments to run smoothly. I’ve also gone on calls to clients though, where they had a pair of matching sets that just wouldn’t play together period. Didn’t matter what I tried and I’m relatively savvy and comfortable with DRAM and making adjustments of voltages, primary, secondary and even tertiary timings.
When you see and hear these types of claims, they are often accompanied some relatively decent advice like:
A.) Get the same exact model.
B.) Make sure the frequency/data rate, timings and voltages match.
Decent advice if you HAVE TO MIX DRAM and it possibly can improve your chances – but wish these folks would throw in a disclaimer that there are no guarantees. Let’s face it, if the manufacturer of the DRAM won’t guarantee that two identical sets of theirs will play together – how can Joe “I know everything” Blow off the street guarantee they will play nice?
Why can it be such a problem you ask? After all, they are the same frequency, timings, voltage – so they are the same right? Far from it….
DRAM is made up (basically) of memory chips that are soldered to a PCB for a simplistic explanation, that is driven with electricity. During the course of a production run of DRAM sticks of a given model, they might be finishing up a large section of PCB that has been cut to the DIMM size and switch to a new PCB that was from a different production lot of the PCB material, which can provide ever so slightly different properties, than the previous PCB used. Same can happen with the physical solder being used, or they may change to a completely different kind, which has ever so slightly different conductivity properties. Then there are the chips themselves, when made by the actual chip manufacturer the chips are binned by the manufacturer as to quality. Let’s take a closer theoretical look at this.
A single production lot may result in say 1,000 memory chips. These are then separated or binned to a number of levels. We’ll say to a fair degree of maybe 4 levels – A through D. We’ll say A (200 chips) is entry level, B (350 chips) is a little better, C (300 chips) even better and D (150 chips) are the best chips. They then sell these chips to two separate manufacturers; we’ll sell them to Wiley Coyote’s favorite manufacture ACME and the rest to our second company who we’ll call Deluxe DRAM (a highly rated company….. Of that production lot ACME might buy all the A chips (for the lower prices) most of the B and a few of the C chips, then the Deluxe DRAM company buys the rest, so each company has an equal amount of chips 500.
ACME get their chips and decides they can make 60 sticks so they simply make 15 ea. of 1333, 1600, 1866, and 2133….and start with A binned chips and use them till they run out, then move to the B sticks and on up. Since they bought very few of the better chips, then some of their 2133 sticks are using C rated chips, most of their 1866 sticks are made with a combination of B-C chips then finally the 1333 and 1600 sticks are from a combination of A and B chips.
Across the street Deluxe DRAM takes their new chips and further separates them to their own specs and they might end up after the binning process with 5 separate groups of chips, adding a E category to the existing, they then make 1333 sticks out of the A chips, 1600 out of the B etc. and have some bonus high end 2400 sticks.
When they each go to make their sticks, Deluxe DRAM gets high end PCBs and solder, and ACME (while I won’t say they buy cheap, but they might), takes a different route and buys different PCBs and a different brand of solder. Also each use their own production equipment and have their own specs as to how much solder is used, the temps they have things set at etc.
Once the sticks are made, each manufacturer then takes the sticks and test them as to their tolerances and match/test the sticks further to a point where they know the sticks that go together in a given package will play together – and they guarantee those sticks in that package to play together. (It’s possible that they might even plan to get say four 4 stick sets out of a given production lot – and not be able to find four sets of 4 sticks that will play together. (In than given scenario, you can see where if you buy two packages of 2 sticks they might not play, and is why the manufacturers won’t guarantee mixing sets
Further if you were to go out and buy a 1866 stick from each company you effectively are probably getting a different PCB in each, different solder which has variable conducting qualities from the other and quite possibly different graded chips and/or chips from different manufacturers..
Now throw in that there a number of companies making memory chips, which further adds to the questionability of compatibility (and all those other ‘bility’s’ that might play in), and you might start to see why mixing sticks can be and often is problematic.
We also might note that most all newer lines of DRAM use 4Gb memory chips where older lines the norm was 2Gb memory chips. (Whoo! glad that one’s out of the way)

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1. Your motherboard supports 3200 DRAM so you can use any DRAM you want.
Knew that short answer in #11 was too good to last, sigh………. Oh well here we go.
While it’s true if the mobo supports say 3200 DRAM, you can run 3200 sticks on it – however, to run those pricy 3200 sticks at 3200 you need a CPU that can handle 3200; else your pricy sticks may only run at 1333, 1600 or 1866 at best.
All too often the statement is made as shown above (and believed) at face value. This is yet again a misrepresentation without including the qualifier add-on of “You need a CPU that can run DRAM at that data rate”.
This tends to go back to the days of Intel’s socket 775 and earlier. In those days, OCing the CPU and DRAM was primarily controlled by the FSB, if your mobo came in a FSB of 1066 and if left at that, your CPU (we’ll use a Q6600 for an example) would run at its native 2.4GHz, and DRAM was limited to 1066. From there, you OC the CPU by raising the FSB, if you took it to 1333 your CPU would be running at 3 GHz, and you could run DRAM at 1333 (the DRAM was limited to the max of the FSB. Moving the FSB to 1600 took the CPU to 3.6GHz and you could run 1600 DRAM, at this time the MC (memory controller) was in the chipset (most often the NB (NorthBridge)) of the mobo. When the newer sockets and CPUs followed the 775 socket, the MC was moved to the CPU.
These days the MC is in the CPU, so while yes, you can basically run any advertised frequency/data rate of DRAM, one must keep in mind, if you want it to run at advertised specs the MC, thus the CPU is more the primary factor in how high of DRAM you can run. As an example current Haswell CPUs are rated at 1600 DRAM and mid to upper tier non-K CPUs can typically run 1866 and up to 2133 sticks fairly reliably. Then for higher data rate DRAM a “K” model is preferred as if can be OCed itself and running faster helps the MC along in running even higher data rate DRAM.
AMD’s current CPU line – the FX models, are rated as “UP TO 1866 at 1 DIMM PER CHANNEL”, however, you may find yourself running into problems with the lower end (and at times the higher end CPUs even running 1866), this in part is due to the MC in the FX CPUs being more native to 1333 DRAM (according to their BIOS and Kernel Programming Guide). As with any CPU, the individual FX CPUs can be OCed to run even higher than 1866, but mileage will vary, I myself was surprised when I did the “Not Just Another DAMN DRAM Review” review/article, that my 8370/Crosshair Formula rig, was able to run all the 32GB sets of 2400, with a fairly conservatively small OC to 4.3.

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