Intel has been quick to release information about its coming microarchitecture and up until now we’ve seen technical analysis to performance previews of Nehalem, but Intel has been sitting on the really juicy details the longest. During IDF it decided to stand up and make more or less everything visible. Anandtech has published the most extensive sum-up we’ve seen so far.
Intel has shared detailed information on the integrated DDR3 memory controller that through its three channels will give Nehalem a monstrous memory bandwidth. To make sure the bandwidth comes to good use, Intel had to revise the internal data bus. The solution was Quick Path Interconnect (QPI), which is quite similar to the HyperTransport technology used by AMD. The high-end version of Nehalem will have two QPI links sporting a bandwidth of 25.6GB/s per link. The mid-range version of Nehalem has to settle for one QPI link.
Other interesting features include the reintroduction of HyperThreading, which will be much more efficient with Nehalem than with the older version used with the NetBurst (Pentium D/4)architecture.
Turbo Mode is also something we’ve heard about before, but it has nothing to do with HyperThreading, even though HT is returning. This Turbo Mode was actually seen with Intel’s mobile Penryn processor already. The technology makes it possible to increase the clock frequency of one core by one notch (133MHz), as long as this won’t break the TDP envelope.
With single-threaded applications idles cores will be inactivated while the active core will be overclocked. Today this automatic overclock moves up the frequency by 266MHz (two notches), but it’s possible to make the Turbo Mode effect even higher. The overclocking headroom with Intel’s processors have been quite big for a generation or two, so there might be more notches up the ladder.
I you want a better overview of the Nehalem architecture and Intel’s new Core i7 series we recommend Anandtech’s recent article. It’s pretty clear that Intel is focusing on making Nehalem a better processor for servers, but there is most likely little to be disappointed with on the performance side of things.
No active posts found.