Saving Smart: 2 x 2GB in an LGA1366 System
3GB of RAM do not look too good in a system based on a high-performance Core i7 processor. The today’s “de facto” standard is to use 4GB of memory. And the CPU-Z results statistics proves it.
When LGA775 systems were all over the place, it was considered decent to equip your system with two 2GB memory sticks. After that it is psychologically hard to go to one 1GB smaller memory size. However, the price of 6GB DDR3 SDRAM kits, like Corsair Dominator TR3X6G1600C8D, is pretty high and may make it difficult for them to win the market. Especially, since there are not too many enthusiasts who would need so much memory.
In this case, it is absolutely natural to try and use dual-channel memory kits of 2GB modules in the new LGA1366 systems. And even though the Core i7 memory controller will not work at its full speed, it is possible that having fewer active channels will not have too serious of an influence on the resulting performance. And it will let us conclude if it makes sense to equip new generation systems with 4GB of RAM instead of 3GB or 6GB.
Well, benchmarks will help us answer this question once and for all. For our experiments on the above described platform using a 4GHz Core i7-920 processor we took two 2GB DDR3-1600 SDRAM modules and compared the results with those obtained on the exact same system equipped with three modules like that.
First let’s check out synthetic benchmarks.
The results are absolutely astounding. Despite our expectations and 33% lower theoretical bandwidth, having two memory channels instead of three cost us only 2% of the practical bandwidth. As for the latency, it didn’t get any lower at all. So, the results difference in real applications may turn out quite small.
Let’s check it out now.
Now that we have just discussed the performance in synthetic benchmarks, the obtained results seem to be absolutely logical. But nevertheless, we can’t deny that the performance difference between dual- and triple-channel memory is truly minimal. Dual-channel DDR3-1600 SDRAM falls only 2% behind triple-channel memory with identical timings settings even in multi-threading test, which is very sensitive to the memory subsystem performance. And if we consider the average results of the CustomPC Benchmark, the average advantage of three memory channels vs. two will be less than 1%.