Intel's new processors with the Core micro-architecture remain in the focus of PC enthusiasts' attention. Numerous tests have proved that Core 2 Duo processors deliver unrivalled performance at their default frequencies as well as at overclocking. No wonder that various modifications of Core 2 Duo and Core 2 Extreme are on the wish list of many users who are upgrading their computers with their own hands. A mass transition to the new Core 2 platform is just about to begin if it hasn't begun already. Our intent now is to review the Core 2 Duo infrastructure to see what is the best environment for that processor.
In this first article we are going to talk about system memory with respect to the Core 2 Duo, particularly we will try to find out which memory parameter has a bigger effect on performance of Core 2 Duo systems, bandwidth or latency. As a result, we will come up with some general conclusions as to what exactly memory out of the variety of DDR2 SDRAM available today suits best for the new platform. Besides, we will give you our own recommendations on purchasing DDR2 SDRAM for systems with new Intel Core 2 Duo processors.
Intel Core 2 Duo and System Memory
Before proceeding to discuss the results of our tests which may give us exhaustive answers to all the questions asked in the introduction, we want to say a few words on why Core 2 Duo processors may put forth specific requirements to the memory subsystem to achieve maximum performance. After all, these CPUs are compatible with the same LGA775 platforms (with minor variations in electric characteristics) that long- and deep-studied processors from the Pentium 4 and D families were used on earlier. But as a matter of fact, the Core 2 Duo has a dramatically different micro-architecture which is the main reason for its different way of working with system RAM.
First of all, the Core 2's innovative dual-core design with a shared L2 cache comes to mind. As opposed to separate L2 caches, a shared L2 cache frees the front-side bus and the memory bus from data transfers required to maintain cache data coherency. Dual-core Pentium D processors used to utilize the front-side and memory buses to exchange data between the execution cores whereas the Core 2 Duo achieves this by means of its shared L2 cache alone. As a result, the Core 2 Duo can use the CPU-memory link to more effect, freeing it from auxiliary data transfers.
The second thing that turned out to have a positive effect on memory performance in Core 2 Duo systems is the increased frequency of the Quad Pumped Bus which connects the CPU and the chipset's North Bridge. The resulting frequency of this bus is now 1067MHz which provides a bandwidth of 8.5GB/s. It also means that Core 2 Duo platforms have an opportunity to fully utilize the bandwidth provided by a dual-channel memory subsystem with DDR2-533 SDRAM modules. Installing even higher-frequency modules can give a chance to additionally reduce memory access latencies.
We shouldn't also forget that the Core micro-architecture features a number of technologies that improve the CPU's memory-accessing capability like the memory disambiguation technique and the data pre-fetch algorithms which are much better than those employed in the Pentium 4. You can learn more about these technologies here.