New quad core server CPUs: AMD Barcelona vs. Intel Harpertown

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Introduction

Last week AMD finally, after months of postponing, introduced its quad core Opteron processors, better known by their codename Barcelona. However, AMD is not the only one with a new product; on the first day of the 2007 Fall IDF, Intel will be unveiling its second generation quad core Xeon server processors, which so far has been referred to as Harpertown. Both manufacturers promise better performance than ever before, and both emphasise especially the improvements made when it comes to performance-per-watt. For the past few weeks we have been testing a Dell pre-production Barcelona server and a Supermicro pre-production Harpertown server, in order to find out which of the competing CPU manufacturers has the best offer in the very popular dual socket server market.

The current situation

Before we go into the new processors' specifics, let us first have a look at the current market for this type of product. Last year Intel was the first to switch from dual to quad core CPUs in the server market, with the Xeon 5300 series, codenamed Clovertown. Here is a review of this processor. Just like Intel's current quad core CPUs for the desktop, Clovertown consists of two dual core processors, packaged together. These CPUs are manufactured using Intel's by now proven 65 nanometre process and available with clock frequencies up to 3.0 GHz. Clovertown CPUs come with a total of 8 MB L2 cache, with each dual core sharing 4 MB. This processor is based on the Core Micro-architecture, which is proving to be very successful for Intel in just about every part of the market ranging from notebooks to highend servers. The so called Bensley platform combines the Clovertown processors with Intel's 5000X chipset, which offers two separate 1333 MHz front side busses for the two CPUs in a dual processor server, and offers support for quad channel FB-DIMM memory running at 667 MHz. Intel chose FB-DIMM technology to guarantee high speed even when a very large amount of modules is used; this enables Intel to provide Clovertown servers with up to 64 GB of memory.

In just about every scenario Intel's Clovertowns, with their extra cores and speedy Core architecture, outmatch AMD's current offering, the second generation Opterons on Socket F. Even so there are plenty of applications where AMD comes out the winner. The secret weapon of the Opteron is still its integrated memory controller, which brings the benefits of much higher bandwidth and lower latencies than Intel manages to obtain. Any workload that demands fast memory access, such as database servers, is where AMD can really shine. Existing dual core Opteron CPUs codenamed Santa Rosa (not to be confused with Intel's identically named notebook platform), are by now available at clock speeds up to 3.2 GHz. As Intel is by no means resting on its laurels, it is high time for a successor...