X-bit labs

Workstation Processors Duel: AMD Opteron against Intel Xeon (page 4)

Category: CPU

by Ilya Gavrichenkov

[ 12/21/2005 | 08:44 PM ]

Intel Xeon 3.6GHz

The maximum frequency in the single-core Xeon series has reached 3.8GHz. This is the limit of the NetBurst architecture which is employed in desktop Pentium 4 CPUs as well as in Xeon CPUs for servers and workstations. However the Pentium 4 3.8GHz can be easily found in any shop, while the Xeon 3.8GHz is much harder to spot. We are far from accusing Intel of a paper announcement on September 26, 2005, yet we couldn’t get a sample of the processor for our tests. Intel’s representatives refused our request and our nearby shops couldn’t provide us with this Xeon, either. Instead, Xeons with a clock rate of 3.6GHz are going to perform for you today.

Intel offers two flavors of the Xeon 3.6GHz, with 1 and 2 megabytes of L2 cache, and we got the newer model with the larger cache. Such processors are much alike to the 600 series of the Pentium 4 (on the Prescott-2M core) and are based on the 90nm Nocona core.

Besides the 2MB L2 cache the support of the 800MHz FSB is another distinguishing feature of the Nocona core employed in CPUs for servers and performance workstations. Unlike the Pentium 4, the Xeon began to use that FSB clock rate not very long ago and the transition to the faster FSB is a big step forward because the system bus is commonly considered a bottleneck in Intel’s existing multi-processor architecture. In modern dual-processor Xeon-based configurations the CPUs share the system bus bandwidth and it is through the system bus that they communicate with one another and receive data to be processed (the memory controller in such a system is located in the chipset rather than in the processor).

The Nocona core supports Hyper-Threading, so the Nocona-core Xeon is considered as two virtual CPUs.

Being a relatively new product, the Xeon 3.6GHz on the Nocona core boasts all the recent innovations from Intel, including the 64-bit extensions to the x86 architecture called EM64T, the buffer-overflow-protection technology Execute Disable Bit, and the power management system Enhanced Intel SpeedStep.

The formal specification of the Xeon 3.6GHz follows below:

We’d like to note two things here. First, although the Xeon 3.6GHz is much alike to the Pentium4 660, it requires a special platform and is installed into Socket 604 that only dual-processor mainboards are equipped with. Second, the heat dissipation of the Xeon is higher than that of the competing CPUs from AMD, and it requires more advanced cooling solutions. For example, the Xeon 3.6GHz that we received for our tests comes with an all-copper cooler, while Opterons are quite satisfied with a cooler that only has a copper sole.

CPU-Z has the following to say about the Xeon 3.6GHz:

The utility identifies the processor core wrong for some reason. The Cranford core is employed in Xeon MP CPUs intended for multi-processor configurations. The core of Xeons for dual-processor platforms is codenamed Nocona.

Our dual-processor platform based on Xeon 3.6GHz is regarded by the OS as having four logical processors due to Hyper-Threading.