I'm building a Core i7-860 system which supports dual-channel memory (up to 16 GB in four DIMMs), my target is 8 GB. From the performance perspective, is it better to have two times 4 GB or four times 2 GB?
Four sticks would cause more strain on the memory controller and motherboard chipset. It would take slightly longer for the CPU to add and retrieve data from four sticks as opposed to two.
For this reason, 2 x 4 GB would be faster then 4 x 2 GB.
Credit to garycase at The Hyphenated Site for this answer.
2x4GB will be slightly faster in benchmarks because the motherboard has to relax timings slightly to handle two DIMMs per channel but in real world use you'll never notice a difference. It also can matter if you're overclocking significantly where the second set of DIMMs will limit your ability to push the memory clocks quite as high.
If costs are about the same, 2x4 GB will give you room to expand to 16 GB of memory in the future if you need it. If costs are significantly higher and you don't anticipate needing more RAM, there's no reason not to save money and use 4x2GB instead.
Not my answer but the one that I followed:
This question has come up before in several other forums, but there has never been a good clear answer. Overclocking, upgradability, and temperature aside, I would suspect that 4x2 would be slightly faster than 2x4 because there would be more interleaving. Interleaving means that the data is spread out across more memory chips. While some chips are waiting for their CAS timing cycle to complete, data access can occur from the other chips.
The thing is, it really depends on the northbridge (NB) implementation. The NB must be able to take advantage of interleaving across four DIMMs, and I don't know which NBs do and which don't. I suspect the most of the Xeon NBs can interleave across four DIMMs, in fact most of those NBs require DIMMs to be installed in groups of four. I'm not sure about the consumer NB lines such as P35, 965, and nForce 680i, the answer could be different for each chipset...
I know this does not directly answer your question. I am quite certain that 4x2 will never be slower than 2x4, it will either be the same or faster if the NB supports four-way interleave.
IMHO as your motherboard can support 16GB in total, I would plump for 2x4GB. This then leaves the option of upgrading in future. However bear in mind that if 1 stick fails, you are losing 4GB in one hit.
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protected by slhck Oct 23 '14 at 5:56
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