Intel's Nocona Xeon / Supermicro SuperServer 7044A-82R
Posted on: 08/21/2004 05:00 AM

PCI Express

With the increasing bandwidth demands of today's peripherals and expansion cards, I/O technology was going to have to advance to keep up. Intel, as per usual, took the lead in an initiative to devise such a technology. The result was PCI Express. It's a high-bandwidth, serial interconnect technology that retains backwards software compatibility with existing PCI technology.

To get myself acquainted with the new technology, I spent some time perusing technical documentation from Intel's website. I was looking through a presentation and found this image which compares PCI Express with what it's attempting to replace, the standard PCI bus. Let's take a look:

Finally we're moving away from a single bus through which all data is routed. PCI Express brings the serial, point-to-point connectivity that current and future high-bandwidth devices require. The increase in total available bandwidth is absolutely ridiculous. Each PCI Express lane can provide 250MB/second of sustained bandwidth. This dwarfs what we're accustomed to seeing from 32-bit/33MHz PCI which tops out at a mere 133MB/second.

PCI Express isn't aiming to only replace PCI, but also AGP as the main video card interface. The x16 slot provides approximately 4GB/second of bandwidth which is nearly double that of AGP8x. NVIDIA and ATI have already jumped at the opportunity to utilize this new interface and several cards are available for purchase to use with either your Tumwater/Nocona box or your 915/925-based system.

Of course it's impossible to talk about PCI Express video cards without mentioning the potential for SLI (Scalable Link Interface). Certain motherboards will be coming to market with two x16 slots on board allowing the usage of two video cards in tandem. Remember the good old days where you would connect two Voodoo II 3d accelerators in SLI? The people who enjoyed such a luxury were the envy of their friends. Well thanks to PCI Express, we can get that feeling of superiority all over again. Given the hardware requirements of games like Doom 3, not to mention certain professional applications, such an ability will certainly be welcome by the extreme power users out there.

PCI Express is a step in the right direction and thus far my experience with it has been completely positive.

Intel's Extended Memory 64 Technology

As I stated in my introduction, the success of AMD's Opteron as an affordable 64-bit solution forced Intel to reciprocate with 64-bit technology for its Xeon line of processors. Thus, Extended Memory 64 Technology (EM64T) was born. This addition allows the Xeon to run 64-bit code and access larger amounts of memory above and beyond the typical 32-bit, 4GB limit. 64-bit allows for the theoretical addressing of 16 exabytes (but you only need 640k...) of memory. I say theoretical because in reality neither Opteron or Intel's Nocona allows for the addressing of that much memory. After reading the review over at Hexus.net, it became apparent that Opteron can address around 128GB of memory and Nocona even less than that. Of course, all of this doesn't impact its ability to execute existing 32-bit code, which allows for an easier/gradual adoption of the platform and its 64-bit benefits.

You're not going to purchase a pair of Noconas (or Opterons for that matter) and expect to reap the benefits of EM64T with your current operating system, drivers and applications. The software must go hand-in-hand with the hardware to truly take advantage of the technology. Unfortunately, we're still waiting for Windows XP64 to hit the retail shelves. Until then, we're relegated to using a 64-bit distribution of Linux, FreeBSD or dabbling with one of the various beta's available from Microsoft. Do you like using beta operating systems? Neither do I.

For our benchmarks, I'll be dabbling with one of those beta's to see if we can draw some initial conclusions on what 64-bit technology will do for the Xeon. Linux testing is also something I plan on incorporating but those results will be presented in a separate article.

Now that we've briefly touched on PCI Express and EM64T, let's move on and take a look at this fine piece of hardware that Supermicro was kind enough to send our way for testing.