Intel Skylake DDR3 vs. DDR4 Comparison
Date: December 1, 2015
When leaks about Intel Skylake processors first started appearing about 9 months ago, those of us in the tech community were extremely surprised to hear that this new generation would feature an integrated memory controller (IMC) that would support not only DDR4 but the older DDR3 standard as well. There had never before been an Intel processor with a similar dual mode IMC. Once actually launched, Intel’s official datasheets revealed that Skylake only supported 1.35V DDR3, also known as DDR3L, which makes sense since that was well within the voltage range of enthusiast DDR4 memory kits and thus would not put undue strain on the IMC.
Nevertheless, motherboard manufacturers started announcing Z170 motherboards with standard 1.5V DDR3 memory slots, and they even validated those models with enthusiast memory kits with voltage requirements up to 1.65V. We actually reviewed one of those yesterday, GIGABYTE’s Z170-HD3. Because of this development, Intel took the unusual step of explicitly telling certain websites that 1.5V and above DDR3 memory was not supported as they could not guarantee the long-term health of Skylake’s IMC at those higher memory voltages.
Despite these clear warnings, we still thought that using DDR3 on Skylake would be pretty cool, since it meant that those who already had suitable DDR3 memory kits could upgrade to the Skylake platform without having to expend extra cash on pricey DDR4. Since then the price of DDR4 has crashed to near parity with DDR3, but those on tight budget understandably might still want to carry over their current DDR3 memory kits.
So there are certain risks in reusing your older DDR3 memory kit, but is there a performance penalty? That’s what we are here to find out. When the Haswell-E LGA2011-v3 platform came out with native DDR4 support many people tried to compare DDR3 and DDR4 memory performance in really ham-fisted ways. However, the only way to perform an identical comparison is to have a platform that supports both DDR3 and DDR4 while keeping the same CPU, and we now have that opportunity with Skylake.
Will the cliché that DDR4’s loose memory timings hurts its performance hold true? We don’t think so, and we explained why in our very first DDR4 memory kit review:
|“While these timings might seem incredibly loose when compared to what we are all familiar with on the DDR3 side, it is important to realize that secondary and tertiary memory timings have arguably become an increasingly more important part of memory performance due to improvements in the memory controller. When you combine this truth with the fact that DDR4 memory kits are able to run at more aggressive secondary and tertiary timings, the overall performance disadvantage (if any) is quite minimal.”|
As a result, what we are actually more concerned about is whether DDR3’s lower clock speeds and resulting lack of bandwidth will hold back the performance potential of our flagship quad-core Core i7-6700K. Reusing parts and saving money is great, but not if it results in a bottleneck that chokes the life out of a cutting edge new processor.