We've just installed some new servers to help out with the spam checking of emails. Each of these machines are 1U IBM x3550 servers with dual Xeon E5320 CPUs, each of which contain 4 processor cores. So all up in 2U of space we have 16 CPU cores and 16G of memory.

What's amazing about these machines is just how fast they are. We had just one of these machines setup, and were able to put ALL our email through it, something that previously took 4 separate machines each with dual 3.0Ghz Netburst Xeon CPUs to do.

I did a bit more digging, and it really shows just how good Intels new Core Microarchitecture which the E5320 processors are based on is, and what a huge jump the architecture is over the older Netburst one. Here's a quick comparison of some figures.

Looking at the SPEC CPU2006 benchmark, we see that the perlbench component is basically a run of SpamAssassin against a corpus of spam and ham messages, which pretty much describes exactly what these machines are doing. Lets look at SPEC_rate, which is basically what happens when we parallelise the computing across all available CPU cores, which is something easy to do with servers processing email in parallel.

  • SPECint_rate for a dual CPU 3.8Ghz Netburst
    cores, 2 chips, 2 threads/core) = 27.6
  • SPECint_rate for a dual CPU 1.86Ghz Xeon

    (8 cores, 2 chips, 4 cores/chip) = 103

That's a 4 times increase for a dual CPU machine! If you look at the non-rate figures, you'll see that each 1.86Ghz E5320 core basically equals one of the Netburst 3.8Ghz CPU cores, but because the E5320 has 4 cores per CPU package, it ends up with almost 4 times the performance! And what's the cost difference?

The E5320 is actually cheaper than the Netburst Xeon, and to top it all off, uses less power as well.


  • Irwindale 3.8Ghz = 110W
  • Cloverton E5320 = 80W

A coprehensive smackdown for the new Intel Quad Core processors.


Ok, so it's not quite a fair comparison. The Netburst Xeons also come in dual core variants. Even so, you can guess that a dual core Netburst Xeon is at most double as fast, so still half as fast as the quad core Core Xeon.

From what I can see though, there's been no SPEC2006 CPU submissions for the dual core Netburst parts that operate in a dual cpu mode which probably gives you an idea that they're performance is in no way competitive. There has been a submission for the dual core 7150N in a quad CPU mode however, lets check that.

About the same as the dual CPU E5320 value, but try actually buying one of those CPUs. They're designed entirely for high end servers. Price comparison sites don't really list them, and the initial price was apparently $2622 and used 150W per CPU, so 600W for 4 of them, and you get the same performance (at least for perlbench) as 2 E5320 processors using 80W each, or 160W total.

To top it off, compare a top of the line Quad core Core processor, the X5355

  • Specint_rate for a dual CPU 2.66Ghz Xeon

    (8 cores, 2 chips, 4 cores/chip) = 146

Which costs:

And uses 120W per CPU, or 240W for 2 CPUs. Amazing performance.