Memory Frequency Impact on Performance
Now we’ve reached the main part of this review in which we'll try to estimate the effect of memory subsystem parameters of the LGA1150 platform’s performance in everyday applications. As we proved above, memory timings are a negligible factor even in synthetic benchmarks, so we will only focus on comparing DDR3 SDRAM with different clock rates. There are a lot of DDR3 SDRAM products available now with varying clock rates, so we will benchmark our Haswell-based platform with memory configurations from DDR3-1333 up to DDR-2933 SDRAM. We use the most popular timings for each clock rate. Here’s the full list of our memory configuration variants (dual-channel DDR3 SDRAM):
- DDR3-1333, 9-9-9-24-1N
- DDR3-1600, 9-9-9-24-1N
- DDR3-1866, 9-10-9-28-1N
- DDR3-2133, 11-11-11-31-1N
- DDR3-2400, 11-13-13-31-1N
- DDR3-2666, 11-13-13-35-1N
- DDR3-2933, 12-14-14-35-1N
Besides the memory subsystem, our testbed with a quad-core Haswell-based CPU overclocked to 4.4 GHz always worked at the same settings in this test session.
We’ll start out by measuring the effective bandwidth and latency using the Cache and Memory benchmark from AIDA64 4.20.2820.
By changing your DDR3 frequency, you can change the effective memory bandwidth twofold. We might have expected this, though, as there’s a twofold difference between DDR3-1333 and DDR3-2933 in terms of clock rate and theoretical bandwidth. Surprisingly, the results do not increase linearly depending on frequency: the fastest memory modes do not ensure maximum bandwidth for some reason. The best results are achieved with DDR-2400 and DDR-2666.
The effective latency changes in a different way:
The latency lowers as the clock rate goes up even with the highest-speed DDR3 SDRAM configurations, so overclocker-friendly DDR3-2666 and DDR3-2933 memory may turn out to be useful in everyday applications. Let's check this out right now.
To estimate general performance in typical usage scenarios we use three traces from the popular Futuremark PCMark 8 2.0: Home (typical internet activities + working in text and image editors), Work (office applications + internet), and Creative (serious photo and video content processing, 3D games, heavy internet use).
Fast DDR3 SDRAM configurations do not look superior here. While they were good in the synthetic memory tests, Futuremark PCMark 8 2.0 shows a completely different picture. Judging by the scores, memory subsystem speed hasn’t been improving much in the past decade. The difference between the fast and slow dual-channel DDR3 SDRAM is no larger than 1-2%.
We’ll also carry out some tests in specific applications to get a full picture.