Review: HP Z400

The HP Z400 workstation belies its entry-level price with performance that meets or beats that of its four- and eight-core predecessors.

The HP Z400 is the entry-level computer in HP's new Intel Nehalem-based line, with models starting as low as $969. That's compared to $1,679 for the midlevel Z600 and $1,929 for the high-end Z800. Unlike its higher-end siblings, the Z400 is only available with a single CPU, and it doesn't feature the snazzy new case. It does share the Nehalem-based performance, however, and on certain applications, the Z400 produced impressive results compared to both previous Xeon generations and the dual-processor Z800. (See my review of the HP Z800.)

Briefly, Nehalem is a new CPU technology from Intel that bolsters data throughput to and from system memory and improves core-processing performance. It achieves the latter primarily by adding back hyper-threaded technology (HTT), which appeared on many CPUs prior to the Core 2 Duo line. As you'll see below, the Nehalem line of CPUs includes both four-core and two-core processors, though the two-core processors don't have HTT.

The Z400 HP provided for my testing came configured with a 3.2GHz Intel Xeon W3570 processor, 6GB of memory, 64-bit Windows XP, and an Nvidia Quadro FX4800 with 1.5GB of memory. Price this out on the HP website, and you'll come close to $5,900. This is a bit deceptive, though, because the Quadro FX4800, which contributed nothing to Adobe Creative Suite 4 (CS4) rendering times, added about $1,600 to the base price.

Go with the stock 512MB card and omit the second system drive, which HP supplied so I could test with either 64-bit Vista or XP, and the price drops to a much more reasonable $4,207—about what I paid for my first Intel 80386-based computer back in the last century. The $4,207 price also includes $520 for a 1TB drive, which is both reasonable and necessary for serious production—though I truly hesitate to think about what 1TB of drive space would have cost in 1992.

Though the positioning of the three Nehalem-based systems seems pretty clear (good, better, best), choosing between the Z400 and Z600 is more complicated than you might expect. Bargain hunters might also think that the HP xw4600—based upon Intel's older four-core technology—is a good economic decision, though a relatively cursory examination reveals that this isn't the case. Finally, there are several critical technology details to consider when configuring your Z400, which I'll discuss along with the benchmarks.

Let's start with an overview of HP's three Nehalem-based systems, as shown in Table 1. As you can see, the Z400 has only one CPU socket and uses Intel Xeon 3500 series CPUs, which currently peak at 3.2GHz. The Z600 has two sockets and uses the Intel Xeon 5500 series, which peaks at 3.2GHz. But because of power limitations, the Z600 can only accept CPUs up to 2.93GHz. All the way to the right, the Z800 uses the same CPUs as the Z600, but it can accept up to 3.2GHz.

For the comparison, this means that the fastest single-CPU Z600 will be about 10 percent slower than the fastest Z400 (2.93GHz vs. 3.2GHz) and will cost about $1,000 more ($5,176 to $4,207), even with the slower CPU. While the Z600 can accept more RAM than the Z400, the maximum of 16GB should be fine for most digital-content-creation (DCC) applications, though the extra 8GB the Z600 can handle could come in handy for data visualization and other large-data-set applications. For most DCC applications, if you're looking for the fastest single-CPU system and don't anticipate purchasing a second CPU, the Z400 is a better choice, especially with its greater internal expandability.

Table 1. Comparing HP''s new Nehalem-based workstation line.

As mentioned above, HP continues to offer the quad-core xw4600, which is based on the older Xeon technology. Though you would expect this system to cost less than the new one, the HP-supplied price came out to $4,548—which is $341 more than that of the Z400. The benchmark results below include tests performed with a 3.0GHz xw4600, though it was running 32-bit Windows XP, so the test isn't apples-to-apples.

Still, even in tests in which memory limitations didn't appear to play a role in performance, the Z400 handily outperformed the xw4600. Given that the xw4600 costs more, the only reason to purchase this unit would be if you previously standardized on the configuration and need to complete a bulk purchase. In all other instances, go with the Z400.

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There are several factors to consider when choosing a CPU for the Z400. First, you can buy dual- or quad-core configurations, as shown in the technical specifications list. Note that the dual-core configurations do not include either HTT or Turbo mode. Not only are the quad-core configurations faster, HTT doubles the number of cores—which, in some applications, should really pay dividends.

Also note that the fastest CPU, the 3.2GHz W3570, uses 1333MHz memory with a QuickPath Interconnect (QPI) bandwidth of 6.4 Gigatransfers per second (GTps). If you drop down to the W3540, not only do you lose about 10 percent in CPU speed, you also use slower memory and have slower transfer to and from other system components. It's tough to guess at the performance reduction this could produce, but theoretically, in a bandwidth-limited application, it could be up to 25 percent, so choose your processor carefully.

Finally, when choosing a memory configuration for any of the Nehalem-based computers, remember that the integrated memory controller has three channels, which means that ideally you'd have three banks of memory at identical values, such as the 6GB of memory (2GB on each channel) that HP shipped with my test system. But what will you do if you need more memory?

You can add a fourth 2GB dual inline memory module (DIMM) to the fourth slot on the system, though this could theoretically slow performance in applications that aren't memory-bound. That's because two DIMMs would share the same memory channel, essentially halving the throughput. On the other hand, if you're working with an application that needs more than 6GB of memory and you didn't add the extra 2GB, your system might have to page data back and forth to your hard disk, which would be much slower than operating with 8GB of RAM in the four slots.

I didn't run any benchmarks comparing performance between 6GB and 8GB of RAM, so I can't really size the problem for you. Fortunately, the problem should be minimized by summer 2009, when 4GB 1333MHz DIMMs become available. (12GB should suffice for most DCC applications.) In the meantime, now you know why HP pushes memories in blocks of three, not two or four as with previous systems.

I tested the Z400 against multiple systems as detailed below. There's a mix of operating systems and RAM configurations, which confounds an apples-to-apples comparison, but you test what you've got. Here are the details on the test systems:

• HP Z800: Two 3.2GHz Intel Xeon 5580 quad-core processors with 18GB of RAM, running 64-bit Vista;
• HP Z400: One 3.2GHz Intel Xeon 3570 quad-core processor with 6GB of RAM, running 64-bit XP;
• HP xw8600: Two 3.33GHz Intel Xeon 5470 quad-core processors with 16GB of RAM, running 64-bit Vista;
• HP xw6600: Two 2.83GHz Intel Xeon E5440 quad-core processors with 3GB of RAM, running 32-bit XP
• HP xw4600: One 3.0GHz Intel Core 2 Extreme Q6850 quad-core processor with 3GB of RAM, running 32-bit XP.

Table 2. Adobe Premiere Pro/Media Encoder benchmarks.

I ran three tests in Adobe Premiere Pro/Media Encoder, two real-world and one synthetic. The first real-world test involved rendering a 90-minute ballet shot with two HDV cameras to DVD-compatible MPEG-2. The editing was relatively modest, so this was a good test of Nehalem's expanded data-throughput capabilities, and both Nehalem-based systems really shone. In fact, the Z400 actually outperformed the dual-CPU xw8600, a theme we'll see repeated throughout these tests. Both 32-bit workstations crashed during rendering, probably because memory usage was too much for the systems to handle.

The next test was a 10-minute single-camera SD shoot ("Loose Strings") rendered to H.264. You can tell that this test was not particularly memory-intensive because the rendering time for the xw6600—running 32-bit windows with 3GB of memory—was only about 10 percent slower than the xw8600, which was running 64-bit Windows with 16GB of memory. Compare this to the third test, which was specifically designed to stress memory usage. In that one, the xw8600 was more than five times faster than the xw6600.

Memory usage wasn't an issue in the SD-to-H.264 test, so it's a fair comparison between the Z400 and xw4600, and the Z400 rendered in just less than half the time of the older system. Again, unless you're locked into a volume-buying agreement, purchasing an xw4600 for DCC doesn't seem to make sense.

The Red One-Dynamic Link test involved a 60-second project with a greenscreen overlay imported from Adobe After Effects via Dynamic Link. It was designed to stress memory usage, and it clearly did judging from the results of the two 32-bit systems. Impressively, the Z400 again outperformed the dual-processor xw8600.

Table 3. Rhozet Carbon Coder benchmarks.

The other tests I ran involved the batch-encoding tool Rhozet Carbon Coder, which is a highly efficient multithreaded program with most formats. In the first test, I encoded 16 files to H.264, VC-1, and VP6, and again, the Z400 performed slightly better than the dual-processor xw8600. Scores were in a relatively tight range, however, which I attribute to long VC-1 rendering times. I noticed in the Windows Performance Monitor that CPU use was poor during these tests.

I encoded all 16 files to a single H.264 preset in the second test and to a single VP6 preset in the third, where CPU use was near 100 percent for the duration of encoding. As you can see, when considering the results of both tests, the Z400 outperformed the dual-CPU xw8600 and proved greatly superior to the xw4600.

There were several tests where the dual-CPU Z800 really shone, including rendering the 90-minute real-world ballet project, but the Z400 was never a slouch, beating both older dual-CPU systems in 11 out of 12 tests. That's impressive for both the CPU and the workstation that houses it.

Company: HP

www.hp.com/workstations

Product: Z400

Assets: Intel Nehalem processors; nearly as fast as the HP Z800 in some tasks; less expensive than some older quad-core workstations; outperforms some older eight-core workstations.

Caveats: Does not share the new case design of the HP Z800 series; certain speed-enhancing technologies only available on most expensive processor.

Price: Starting at $969