Originally Posted by os2wiz
iF you get 2 memory kits each with 2 dimms of the same sku, they will not always work well together. That is because they are not perfectly binned to match each other. I know this from my own experience . I have 2 kits G.Skill DDR4- 4266 CL19-19-19-39. Same sku each with Samsung b-die chips according to Thaiphoon. I use each kit solo and overclock the memory in bios. One kit at 3600mhz will allow me 16-16-16-36 the other 16-17-17-37 with stability testing confirmed. So they show intrinsic differences although both binned to boot in a particular motherboard with a particular model cpu with XMP. Now if I put these 4 dimms to occupy all 4 dimm slots on my daisy-chained board it will define the maximum speed and settings by the dimms with the slowest timings, the least common denominator. This is based on logic as well as empirical observation. So no it is NOT voodoo but there are still differences between dimms within the same model and sku number. I do not worship Gurus. I will show respect to those who have a level of expertise but they are not gods. When you stop thinking and behave solely by rote thinking you are underselling your capabilities. Always follow your gut instinct and accumulated knowledge and realize there is somebody else out there who may know a bit more whether recognized or acclaimed or just quietly acquiring knowledge by experience.
If using all 4 dimm slots the 4 dimms must be machine matched by the memory manufacturer. They must be bought as a set of 4 dimms.
I'm just picking your brain because I was puzzled by your remark on why you should never combine two kits. See, by saying "they will not always work well together", you're implying that there will be inherent
issues with running two separate kits together. But that's not the case, of course - that's what I meant with the 'voodoo' remark.
In reality, if
4-dimm kits are as carefully binned as you claim, all you're achieving is that your sticks all OC roughly the same. BUT! That might as well be worse than the 2 separate kits, there's no guarantee your 4-dimm kit is a better bin than the 2-dimm kits. It's still simply a lottery. Indeed the logic is simple. This 4-stick kit might as well only do the 16-17-17-37 timings, and you'd never have known a different kit could've been faster. At the same time, 2 separate kits where one does 16-16-16-36 and the other does 16-17-17-37, will be limited by the 16-17-17-37 kit but as a whole perform exactly the same as the 16-17-17-37 4-stick kit. And you'd be none the wiser, the result is identical. Or the 2 separate kits might both, by sheer luck, be able to do 16-16-16-36, and outperform the 4-stick kit when put together. You can't know. It's a lottery.
But there's no inherent
reason not to put two kits together. And nothing states that a 4-dimm kit will always be better binned than two 2-dimm kits - might as well be worse.. From a technological standpoint, two separate kits will work together completely fine.
On another note, have you ever separately tested the dimms from a 4-stick kit to see if one was faster than the other, or did you assume they would be 100% identical in performance anyway?