Memory Scaling on Core i7 - Is DDR3-1066 Really the Best Choice?

We raised the question at the beginning of this article: is there any value in using memory faster than DDR3-1066 on the Core i7 platform? In certain situations that answer is a definite yes and in others we really doubt the actual value of using anything more than a good triple channel DDR3-1066 6GB kit running at tight latencies, at least CAS 7 and preferably CAS 5.

What we discovered is that faster memory certainly makes a splash in our synthetic Everest benchmarks with memory read, write, and copy speeds showing improvement in the 40% range when moving from DDR3-1066 C7 to DDR3-1866 C7. Latency improvements improved by 30% in the same tests. However, we expected this, and for that reason we did not run the standard Super Pi or early 3DMark tests that heavily depend on memory and cache speeds for best results.

Once again, as we moved to real-world applications, those impressive synthetic benchmark improvements did not translate into results that would justify spending three times as much for a memory kit for most people. We had mixed with certain applications like WinRAR producing a 20% improvement from DDR3-1066 C7 to DDR3-1866 C7 while several applications showed minor performance improvements under 2%. If your primary job is to compress and archive files for a living, then the expenditure for fast low latency memory is justifiable. However, the decision to spend additional funds on higher performance memory is quickly up in the air after this point.

In our 3D rendering tests like Cinema 4D R11 and LightWave 3D 9.6, which we know to be sensitive to memory speed, additional memory bandwidth can provide tangible performance improvements of up to 7% or greater. Certainly, our multitasking benchmark showed the benefit of both greater memory and reduced latencies with performance improving 8% as we heavily loaded the system with multiple tasks and a large memory footprint. For users in this category, we have to agree that improving memory bandwidth will be beneficial.

However, common desktop applications such as Excel, Photoshop CS4, iTunes, and others just do not benefit that much from improved memory bandwidth or latencies. That brings us to games. Average frame rate improvements improved up to 7% by increasing bandwidth and reducing latencies but we never noticed the difference when actually playing the game. However, we noticed minimum frame rates improving up to 14% as we increased bandwidth and reduced latencies. This is an important fact as minimum frame rates are a better indicator of performance than averages in most cases. In our particular benches, the improved minimum frame rates took Dawn of War II from being a stutter fest in heavy action sequences to relatively smooth when moving from 1066 C7 to 1333/1600 C6.

Once we overclocked our system, the playing field equalized for the part as latency improvements had just as much impact on performance, if not more so at times, than bandwidth in most of our applications. In fact, in our multitasking test that showed an improvement of 8% at stock speeds, the difference between 1200 C5 to 2000 C8 was only 2%. Even our top responding application, WinRAR, managed just a 4% performance increase when moving from 1200 C5 to 2000 C8 compared to the 20% increase when moving from 1066 to 1866 in the stock test. The increase in CPU speed outweighed any potential gains in memory bandwidth or latency improvements in our benchmarks.

Based on today’s overall results, we have to question the validity or purchasing high-end memory for most users. Whether we like to admit it or not, most of us home users tend to be single task users when it comes to running an important application or game. Sure, we might have a few IM programs open, several browser windows, email, an occasional video or audio application, maybe Word, and then we have a major application like Photoshop or a game open. Although most gamers I know will close just about everything down to get the best video performance, several still run many applications in the background while gaming.

We might consider this multitasking but in reality, we have many programs sitting in the background while concentrating on a single task like Photoshop or Premier Pro as an example. We typically are not encoding last week’s party video in MainConcept Reference, have Cinema 4D R11 and LightWave 3D 9.6 rendering our latest artistic creations, and Photoshop is making us look a lot better in a swimsuit than we ever could while watching the latest BD title with Grandma singing Boom Boom Pow on Skype Video.

Of course, those that are doing all of these activities and more will benefit from purchasing fast low-latency memory and we even suggest getting 12GB while you are at it. For the rest of us, the primary applications we run and whether or not we overclock will have a large say in what is best for us. There is also the budget to consider, as most of us actually have to adhere to one. Looking at it from a budget viewpoint, is it worth paying 225% more for a DDR3-2000 C8 6GB kit over a DDR3-1066 C7 kit for an average performance improvement of 5% across a wide range of today’s most popular applications?

For a significant portion of users who run at stock or near stock speeds with system stability being paramount, we think not. For these users we suggest a DDR3-1066 C7 kit like the one we used from Patriot that has the capability of performing at 1066 C5 with a small bump in voltage and that can reach DDR3-1600 C9 (an excellent comprise setting due to pricing changes this past week) at warranty and system friendly voltages. This allows some growth potential in the system or the ability to increase bandwidth in the future at relativity low cost. Another excellent option in this price range is the GEIL DDR3-1333 C7 6GB kit we used that had no problems running at 1333 C6 or 1600 C8 with a small yet warranty friendly bump in VDimm and VTT. In fact, this particular kit or ones like it hit the performance sweet spot for users wanting very good performance with an eye to future overclocking efforts.

We know there is another section of users, enthusiasts to be exact, who balance their needs between stability but also extracting as much performance out of their systems on air or water cooling who need something more than DDR3-1066, even at CAS5. For these users we highly suggest going with a DDR3-1333 C6 6GB product or one that will do C6 with minimal voltage increases as a base choice. Based on recent price adjustments, a good budget to performance compromise would be DDR3-1600 C9.  However, in individual module testing our 1333 C7/C6 kits had more clocking headroom along with the ability to run lower timings than our 1600 C9 sample. For those who tend to overclock 24/7 while running a multitude of applications, a DDR3-1600 C6 6GB capable kit is our best suggestion without going into debt on the DDR3-2000 kits.

We tend to favor running low-latencies at any given memory speed to ensure the best possible performance and as such we tend to stray from any of the CAS8 or CAS9 kits below DDR3-1866, unless they are capable of running much lower timings on like voltages. As such, we think DDR3-1600 C6 offers the best overall application performance in the market today for the enthusiast if you are willing to pay for it. That could be for a C6 certified kit similar to the ones we used from Mushkin or several of our DDR3-1600 C7 or DDR3-1866/2000 C8 kits had no problems running 1600 C6 with proper VDimm and VTT settings. In the near future, we will review all of the kits utilized today to determine the best value in each category, but for now, consider our choices to be safe ones.

Of course, for the extreme users dedicated to benchmarking, you can toss out all of our recommendations and just go for the DDR3-2000 C7 or better kits. In the end, there is no denying that the Core i7 processor will always perform better when paired high bandwidth low-latency memory. Just how much better depends on the application or situation, but Intel was certainly in the ballpark when they designed this platform around low-latency triple channel DDR3-1066.

You really do not give up that much performance with DDR3-1066 when compared to the more expensive alternatives and that is a good thing to know when putting a system together on a budget. As such, there is still great value in using it. If you have budget freedom, first off I am sure you will be a memory company’s best friend. Secondarily, temper your desires to go straight for the DDR3-2000 kits. It should be a comforting thought that purchasing a DD3-1333 C6 or DDR3-1600 C6 capable kit will offer the balanced performance you are seeking at price that should still allow a night out on the town this month.