Next-Generation Processors and Faster DDR4 RAM Make HP's Latest Workstation a Peak Performer

It has been just two years since HP introduced its flagship Z820 workstation. And, almost like clockwork, we’re ready for a replacement model that updates many of the internal components.

The two-year cycle is no accident. Like the newly introduced Z640 and Z440, the Z840 is timed with the introduction of Intel’s latest generation of Xeon Haswell processors. Along with the bump up in processors, the Z840, Z640, and Z440 are able to take advantage of faster DDR4 memory. The new models include the latest graphics cards from Nvidia and AMD. You can now configure your system with a PCIe-based SSD, which is faster than the standard 6 Gb/s SATA-based SSD. And there are a few other goodies hidden inside the Z840, including the ability to equip any of the 3.5-inch drive bays with two 2.5-inch hard drives—giving you twice the number of internal drives.

Put it all together, and you could have a new top-of-the-line workstation with 36 cores and as much as 1 TB of RAM when 64 GB DIMMs are available in 1Q 2015, or as much as 2 TB of RAM when 128 GB DIMMs are available in 3Q 2015. Until then, the maximum would be a not-too-skimpy 256 GB of DDR4 RAM.

Of course, you don’t have to max out your new Z840. The starting price is $2,399, though that system wouldn’t include a discrete graphics card. You could easily spend from $4,000 to $6,000 for a single-processor configuration. And the price will soar quickly, once you add a second processor and larger amounts of memory. (Each processor has direct access to its own memory slots, so you’ll want to double the amount of RAM if you opt for a two-processor system.)

Buyer’s Remorse?
If you bought a previous-generation Z820, you may be feeling kind of low right now. And you may be wondering, just how much faster will a Z840 be compared with a Z820? As they say—it depends. The DDR4 memory in the Z840 runs at 2,133 MHz versus a top speed of 1,866 MHz speed for the DDR3 memory in the Z820. That’s a frequency difference of about 14 percent.

With a maximum 36 cores (with 72 threads) in the Z840 versus a maximum 24 cores (with 48 threads) in the Z820, the Z840 can process 50 percent more data than the Z820, at least in theory. In reality, the high-end multi-core processors often have a slower clock speed than the less expensive processors with fewer cores. For example, the fastest 18-core Xeon processor (the E5-2699 v3) has a clock speed of 2.3 GHz, which is considerably slower than the 3.5 GHz clock speed for the fastest 4-core Xeon processor (the E5-2637 v3).

If you work with massive video projects, and your software fully supports multi-core hyper-threading, you could see a substantial leap in performance with a fully equipped 36-core Z840 versus a fully equipped 24-core Z820. For everyone else, there should still be a significant increase in speed. A typical Z840 workstation user might see a 10- to 30-percent boost, given the faster processors (per dollar spent), higher-frequency DDR4 RAM, faster graphics cards (per dollar spent), and speedier SSD—versus a two-year-old Z820. The actual increase would vary according to the type of work you do and how you configure your new system to match your workload.

Why Not a Z640?
What about the choice between the flagship Z840 and the next-level-down Z640? The Z640 currently has an entry price of $1,759 (versus $2,399). Like the Z840. it’s compatible with the latest 18-core Xeon Haswell processors. And it can be equipped with either one or two processors. On the downside, the Z640 isn’t compatible with the fast, more power-hungry 160-watt Xeon processors. It tops out with the 145-watt processors. The Z640 has six expansion slots versus the eight slots (seven active, one mechanical) in the Z840. The Z640 does still have a legacy PCI slot, if you have a PCI card that you need to use (the Z840 is strictly PCI Express). The Z640 has 8 memory slots versus the 16 in the Z840 and five expansion bays versus six in the Z840. None of these differences are terribly restrictive, though during the life of your system you may want the additional flexibility to expand the memory and storage to keep pace with 4K, 6K, or even 8K video.

There will always be tradeoffs in price versus performance—both for the entry price of the workstation and how you initially equip it. Fortunately, most of the components in the Z840 can be user-upgraded—including the processor or processors—because of the tool-less chassis (a carryover from the original Z800). You probably won’t be able to upgrade to DDR5 memory or the next-generation Xeon processors. However, you could purchase your new Z840 with a single processor, 16 GB of RAM, and a modest SSD drive. Then later, you could add a second processor, extra RAM, and additional storage, without having to discard any of the original components.

Note the improved CPU heat sinks for more efficient air-cooling. Click image to load a high-resolution version.

Swapping out those two processors for two 2.3 GHz Xeon E5-2699 v3 processors (for 32 cores and 72 threads) would have added $11,360 to the system price. Similarly, opting for a single processor rather than two would have lowered the price $1,720. You can go to the HP website and try out different configurations. You could evaluate your own needs, find the appropriate components, and see what price you come up with. Or you could select the combination of components that fit your budget. Either way, configuring your own system will give you the flexibility to get the most for your money.

Quiet, Please
I’ve been using a Z820 as my main workstation for the past two years, so I was especially interested in what improvements HP might bring to the Z8 series and how those improvements might affect the acoustics of the system. According to HP, it should have the same or better acoustic performance as a Z820. That would be quite an accomplishment because of the faster components in the Z840. I didn’t do a direct sound-level comparison between my current Z820 and the Z840 review unit, because my Z820 is packed to the gills with hard drives, along with mismatches in processors, memory, and graphics cards. What I can verify is that the Z840 seemed very quiet given its configuration. It’s likely that it would remain impressively so as you upgrade or add components over the years.

In this regard, a notable difference between the two Z8 systems is the lack of a liquid-cooling option for the Z840. With the Z820, liquid cooling was required for configurations that included a 150-watt processor, specifically the 3.1 GHz Xeon E5-2687W. Because the air-cooled heat sinks are more efficient in the Z840, there’s no need—or even the option—to switch to liquid cooling, even when you configure the Z840 with two of the new 160-watt processors. There is one disadvantage to the lack of a liquid cooling option. You could order it for a Z820 even when it wasn’t needed, in order to reduce the noise to the lowest possible level. That’s no longer possible with the Z840, though this would be desirable only in situations where the noise levels are critical for your work environment.

Other Improvements
As previously mentioned, HP has redesigned the internal drive bays for the Z840. Each of the four 3.5-inch drive bays can alternatively house two 2.5-inch drives. In other words, the four internal bays can hold four 3.5-inch hard drives or eight 2.5-inch hard drives—or various combinations of 3.5-inch and 2.5-inch drives. With the Z820, you could install a 2.5-inch drive into a 3.5-inch bay, but it would take up the entire bay rather than half a bay.

Why would you want to use 2.5-inch drives, given that a currently maxed-out Z840 storage system would consist entirely of 3.5-inch drives? There are two reasons. In the future, 2.5-inch hard drives will likely grow in capacity faster proportionally than 3.5-inch drives, to the point where a maxed-out configuration might favor the 2.5-inch drives. And using 2.5-inch drives gives you additional flexibility if you tend to swap out drives by project and have multiple projects going on simultaneously.

Another difference: There are now four USB 3.0 ports in front (as opposed to two 3.0 ports and one 2.0 port on the front of the Z820). The external 1394a port is gone, though you can add it back by ordering it as an add-in card. And, as previously mentioned, the legacy PCI slot is now a part of history as far as HP’s flagship model is concerned. Interestingly, the PS/2 and serial ports are still there, in case you want to use your old mouse or keyboard.

In the category of small irritations that can lead to big frustrations, I’ve always disliked the LED light that’s embedded in the Z820’s front on/off switch. It’s bright blue and far more intense than it needs to be, especially in a darkened room, where it can be distracting. If you’ve felt the same way, you’ll be very happy with the redesigned on/off switch on the Z840. The embedded light is now a soft white, and it’s no brighter than it needs to be.

By the Numbers
While it’s important to run benchmarks in order to compare the performance of one workstation with another, it’s also important to understand that you can configure a Z840 or any other made-to-order workstation to produce a wide range of results. Again, it’s always a tradeoff between price and performance. You could configure a Z440 to outperform an Z840—and that Z440 might cost considerably more than the Z840—but what would be the point? The Z840 is designed so that it can be expanded as far as a PC-based workstation can be configured. How much you choose to spend, and on which components, is up to you.

Keep in mind that we chose to equip the review unit with two processors and a PCIe-based SSD. It’s also a roughly $7,000 configuration, as opposed to a $3,000 or $10,000 configuration. Those other configurations would have given a very different set of benchmark results. And how you choose to configure the individual components in your $7,000 system—emphasizing extra memory over processor speed, for example—would also affect the results of the benchmarks.

As you might expect, the Z840 performed much better than the Z820 that I reviewed two years ago, especially in those tests where the faster components come into play. With the 64-bit version of Cinebench 11.5, the Z820 turned in a speedy 58.07 fps on the Open GL test. That was left far behind by the newer Z840, which racked up a truly impressive 112.43 fps. Similarly, on the Cinebench CPU benchmark, the Z820 had sped through the various processor-related tasks to chalk up 16.74 points. As powerful as that seemed two years ago, the Z840 pushed even further this year with its score of 23.46 points. Cinebench is an excellent benchmark for evaluating graphics rendering. It’s available for free online, so you could run it on your current system to determine how your workstation might compare with this particular Z840 configuration.

With PCMark Vantage, the Z840 showed only moderate gains over the Z820. This is a more generalized benchmark designed to test a PC’s ability to work with photos, video, and music, as well as tasks related to games, communications, productivity, and security. The Z840’s score of 18,191 was only about 4 percent better than the Z820’s 17,453 score, most likely because some of the tests received only a marginal benefit from the higher clock speed and faster memory. Like Cinebench, PCMark Vantage is available in a free version.

Conclusion
It’s hard to find fault with the HP Z840. If you’re a Mac user, you may wonder why there isn’t an onboard Thunderbolt connector. HP does support Thunderbolt 2, though that support is limited to an optional add-in card. You might just want a different configuration of drive bays or expansion slots than is offered in the Z840. Some people still need legacy support for an old PCI card. Or you may have a 1394-based video device that you use almost daily.

That said, this is a substantial upgrade to the Z8 series workstation, primarily due to the recent advances in the Xeon processors and faster DDR4 memory. The new PCIe-based SSD option could be desirable if your work depends heavily on spooling large files from your hard drive. For companies that swap out projects or crews on workstations, the possibility of converting from 3.5-inch to 2.5-inch hard drives could be important. And if you work with large video projects that you prefer to keep entirely in memory while editing, the ability to stock your workstation with 64 GB DIMMs or even 128 GB DIMMs (when available) could make this an easy purchase.

Bottom line: Until something new and unexpected comes down the pike, the HP Z840 is the current top choice in workstations. It’s designed to handle just about anything you can throw at it.