Although we’ve got memory kits with a combined capacity of 8 and 16 gigabytes, we don’t want to focus on the difference in their performance. It is only in specific applications that the extra 8 GB of system memory can show up but everyday applications don’t really need too much memory. 4 GB is quite enough for a modern computer. Increasing the amount of system memory above 8 gigabytes may only be required for specific applications like running multiple virtual machines or for the purpose of accumulating some reserve of memory while it's cheap. Anyway, if you install 16 GB in your computer, you should know what you need it for, but we will focus on the effect of such factors as memory timings and frequency instead.
In our performance tests we checked out the speed of our LGA1155 platform with different dual-channel memory kits. Each kit was tested in two modes: 1) automatic configuring (every timing is set by the mainboard's BIOS according to the XMP data) and 2) highest clock rates and best timings (as achieved in our overclocking tests above) set up manually in the mainboard’s BIOS.
First of all we want to run synthetic benchmarks of memory bandwidth and latency. We will use the MaxxMEM2 suite which can run both in single- and multithreaded mode.
The clock rate of DDR3 SDRAM does affect memory subsystem parameters on Ivy Bridge platforms. For example, increasing the clock rate by 333 MHz helps improve the practical bandwidth and latency by 5-7% with single-threaded access. The speed of multi-threaded access grows up even more, by 15-20%.
We can also see that the memory modules with identical specs but different capacity differ somewhat in performance. For example, the 8 GB DDR3-1600 kit is faster than the 16 GB DDR3-1600 kit in terms of latency and bandwidth by up to 5%.
It seems that overclocking your memory subsystem and purchasing high-speed DDR3 SDRAM makes some sense, but don’t forget that the diagram is based on synthetic benchmarks. We don't usually see such a sharp difference in real-life applications. Anyway, we guess we need to take a look at some real tasks that use system memory intensively.
In some usage scenarios high-speed overclocker-friendly memory can indeed be useful, especially if it isn't much more expensive than ordinary products. Memory subsystem parameters can affect the speed of gaming applications, too.
Of course, a game's frame rate depends on the graphics subsystem performance in the first place. However, we shouldn’t underestimate the significance of the memory sub-system parameters, and its high operational speed may help you increase your gaming PC's performance by a few percent. So, choosing the right memory is important. And the most important factor about DDR3 SDRAM is its clock rate. The large capacity may even negate the benefits of overclocking. The gaming tests show that the memory kits consisting of 8 GB modules are somewhat slower than their one with 4 GB modules.