The Xeon 5160 (a.k.a. Woodcrest) is probably the best server chip Intel has made in the past decade. It delivers high IPC, high (3GHz) clock speed and a surprising low 80W TDP for a dual core design. But Intel's engineers saw that the fastest Woodcrest could score twice for Intel, in a slightly different form... or should we say package. Lower the voltage of a 3GHz from about 1.21 V to slightly less than 1.1V and you can only achieve 2.33GHz. However by running at 2.33GHz and 1.1V, Intel was able to cut the TDP in half. Now place two of these low voltage Xeons in one package and you get a 2.33GHz quad core Xeon and an 80W TDP. This is the essence of the CPU that bears the codename "Clovertown".
The quad core Xeon runs at less than 1.1V
The really weird thing about all this is that Intel sells those two Xeon 5160 chips with lower voltage for the same price as one of the higher clocked chips. A 2.33GHz quad core Xeon DP costs the same as a 3GHz dual core Xeon DP ($851), and a 1.86GHz quad core will cost as much as a 2.66GHz dual core. In other words, Intel is willing to give one chip "for free" just to "ignite the quad core era".
Intel is also trading in (theoretically almost 30%) single threaded performance for more multi-threaded processing power while keeping the power envelope the same. It is not as radical as Sun's T1, but the philosophy behind it is more or less the same. Is it a good bet? Well, being first to market with a quad core x86 product will probably make a big impact. It should be especially interesting for HPC and rendering applications. If you need the power of four cores in a blade server, the 65nm Clovertown or Xeon 53xx is the ideal CPU for the very crammed, "hard-to-cool" housing.
The Xeon 53xx - with the appropriate BIOS update - should have drop-in capability in 5000(x) based chipset boards. The availability of Xeon 53xx generates some very interesting choices for the server buyer. With 8 cores on a dual socket system, can it replace the more expensive quad socket systems such as those based on the Opteron 8 series or the recently launched Xeon 71xx CPUs? Should you go for a high clocked dual core Xeon or a lower clocked quad core Xeon? The "standard" answer is that it depends on the application, but that answer is boring and hardly informative. In this article we will try to give an answer to these questions as they apply to Rendering, OpenSSL, Java, SAP and MySQL applications. Jason and Ross are busy with the SQL Server benchmarks, so you can expect even more benchmarks soon.