HP's Z2 Tower G4 (starts at $909; $3,499 as tested) is a workstation PC line that spans entry-level (as HP defines it) to rocking power towers. Now in its fourth generation, this mid-tower desktop can be configured with an Intel Core- or Xeon-class CPU to meet a wide range of professional needs, from CAD and graphics design to video editing and VR. As we're testing it, with a Core i9-9900K CPU and an Nvidia Quadro RTX 5000 GPU, it's more than up to any of those tasks with aplomb. It stacks up favorably to the competition from Dell's Precision and Lenovo's ThinkStation lines on value and features, and it even includes a standard three-year onsite warranty for peace of mind. All told, the Z2 Tower G4 is an excellent pick for a reliable, high-performance, and not-wildly-expensive desktop workstation PC.
'Entry-Level,' But Powerful
Some clarification around HP's marketing of the Z2 Tower G4 as "entry-level" is required since it's not the company's least-expensive tower workstation. That designation belongs to the Z1 Entry Tower, which isn't a true member of the Z product line, but a rebranded HP EliteDesk desktop with workstation-grade components. The true Z towers, starting with the Z2 Tower G4, are built for continuous loads and demands, and while that's not to say the Z1 couldn't handle the same duties, it's not explicitly designed for them.
Within the Z2 line, the Z2 Tower G4 is the most powerful, with the Z2 Small Form Factor and the Z2 Mini trading performance for size. For the next level of capability, HP offers its tower-only Z4, Z6, and Z8 workstations that scale to levels of performance and pricing that most of us can hardly imagine. (Fun fact: A Z8 Tower can be configured into six-figure pricing.)
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Back to the Z2 Tower G4. It straddles the lines between Lenovo's ThinkStation P330 and its P520/P520c tower workstations. The P330 offers more affordable Intel Core-class processors like the Z2 Tower G4, but it tops out at a Quadro RTX 4000 GPU. Getting the Quadro RTX 5000 to match our HP review unit requires stepping up to the larger P520, which I priced at $4,254 with a similar loadout. It's not an apples-to-apples comparison, though, as the P520 uses a Xeon CPU that requires pricey ECC memory.
It's a similar story with Dell's Precision Workstation line. The Precision 3630 tower offers Core-class processors, but you'd need to step up to the huge Xeon-equipped Precision 5820 tower to get the Quadro RTX 5000 GPU, which I priced at $4,691. So, if you're after maximum Quadro-class GPU performance without needing a Xeon chip or ECC memory, it would seem that HP has carved itself an attractively priced niche with the Z2 Tower G4. (It manages competitive pricing with Xeon chips, too.)
The Design: It's All Utility
The Z2 Tower G4 is compact for a mid-tower, at 17.1 by 14 by 6.7 inches (HWD). The all-black design isn't much of a looker, but that's not necessarily a con for the business and professional audience of this machine. Its only focal point is the plastic front grate on the otherwise-metal tower.
Our review unit has HP's optional grab handle in the 5.25-inch bay, a clever way to make use of a space that would otherwise be taken by a filler plate if no drive is included. HP offers the Z2 Tower G4 with numerous optical-drive readers, if you need one.
The power button, the disk activity light, and the front-panel connectivity are arranged in a strip about two-thirds of the way up. Our review unit has an audio combo jack (headphone/microphone in one) and a pair of USB 3.0 Type-A ports, while the spaces for the USB Type-C port and the SD card reader are filled in with blanks, as our review unit isn't so equipped. (They're $24 and $18 options, respectively, on custom-configured models.) HP told us it doesn't make them standard to keep the tower's pricing as flexible as possible. In other words, if you don't need them, you don't have to pay for them, and they aren't included as a hidden cost. I can see this argument in a business environment, but if this were a consumer-focused PC, it would be unheard of for one in this price range to not have USB-C as standard equipment.
It's easy to pop off the front panel by gently tugging at its bottom edge. Our review unit is equipped with the optional dust filter, which covers the front fan to prevent most particles from getting inside the tower.
In a page out of aftermarket PC cases, the filter is held on by magnets and is washable for simple servicing. It's a great feature on any desktop tower, especially in the business world.
Accessing the interior of the Z2 Tower G4 requires one pull of the handle on the left-side door. It swings outward and away.
It's no surprise that space is tight in here, given the compact nature of this tower. Nonetheless, things are clearly laid out and accessible. The blue ATX motherboard dominates the space; the board has been enhanced for this G4 iteration of the Z2 Tower with better VRMs to handle Intel's 9th Generation CPUs. The Core i9-9900K in our review model is topped by HP's large Z2 Z Cooler...
HP says this cooler is quieter and lets the processor perform better than its standard air cooler. I couldn't verify that, as I didn't have access to the standard cooler, but I can say the Z Cooler does its job well. During a video-encoding test in which I fully stressed the processor for about 6 minutes, the Core i9-9900K maxed out at 83 degrees C, or well under its rated maximum temperature, all the while producing almost no extra noise that I could hear outside the tower.
That said, the Z2 Tower G4 doesn't provide built-in overclocking controls when equipped with an unlocked K-series CPU like the Core i9-9900K in our review unit. I don't consider it a big deal on a workstation like this, since it probably wouldn't be overclocked, anyway, for stability reasons, but the price premium for the K-series CPUs lie mostly in their overclocking potential.
The power supply is top-mounted. A 250-watt model is standard in the baseline configuration, but the potent loadout in our review unit mandates a 650-watt, 80 Plus Gold-certified model, the most powerful choice in the Z2 Tower G4. Its wires are routed, zipped up, and tied off in an orderly fashion. That's not always a given with big-box towers.
The airflow in this tower is front to back. The active intake comes from a fan at the bottom of the front panel, strategically located to send cool air over the graphics card and the two M.2 slots for storage. One of the slots in this review unit is occupied by a 512GB HP Z Turbo drive, which is equipped with a heatsink of its own. A third M.2 slot, hidden behind the graphics card in the photo, is for the optional wireless card. (Our unit isn't so equipped.)
The Z2 Tower G4 takes up to three 2.5-inch or 3.5-inch drives for further storage needs, with this review model featuring one of the latter in a 2TB flavor. HP also provides options for PCI Express card-based SSDs in the two PCI Express slots. For RAM, the Z2 Tower G4 has four DIMM slots for DDR4-2666 memory. Error-correcting code (ECC) memory is available with the Intel Xeon CPU options. Our Core i9-based review unit has a healthy 32GB dual-channel setup via two 16GB DIMMs. The maximum-supported amount is 64GB via four 16GB DIMMs.
Our review unit has Nvidia's professional-grade Quadro RTX 5000 GPU with a whopping 16GB of dedicated memory. It's the most powerful card available in the Z2 Tower G4. I'm not sure exactly what it adds to the price (it wasn't yet a standalone option in HP's configurator), but aftermarket versions go for about $2,100. (Yes, for just the card; welcome to the workstation-hardware world.) Professional GPU options are one of the reasons the Z2 Tower G4 carries independent software vendor (ISV) certifications. The card in our review unit has a blower-style cooler, four DisplayPort video-out connectors, and a VirtualLink USB-C port.
Air exhaust is handled by a rear fan and one in the power supply. Even under heavy load, I found the Z2 Tower G4 produced little in the way of noise, not rising above the level of normal household background noise.
Moving onto connectivity, the motherboard provides a streamlined, but adequate, selection of ports for a mid-tower desktop. There are two USB 2.0 legacy ports, four USB 3.0 Type-A ports, an Ethernet jack, a pair of DisplayPort 1.2 video-out connectors, plus line-in and line-out audio jacks.
The two silver-outlined spaces you can see are for HP's Load Flex port options; this goes back to the whole idea about not equipping the tower with what you don't need to keep costs down. The blank on the top-right is for an optional serial port (not included in our review unit), while the other can accommodate a variety of video-out connectors or other I/O ports (also not filled in our review unit). These can be conveniently added down the line, should your needs change.
The Included Peripherals
The preconfigured Z2 Tower G4 we're reviewing includes a wired USB keyboard and mouse in its price. The two-button mouse has a scroll wheel and an optical sensor, and that's about all there is to say about it. It was comfortable for my usage and seemed durable enough.
Meanwhile, the keyboard isn't a generic model, but HP's USB Premium Keyboard. Note that this keyboard isn't standard across the Z2 Tower G4 line, just on some preconfigured models. (It's optional on configurable models and can be purchased standalone.) Its anodized aluminum surface gives it a solid, almost blade-like feel considering its thinness. The island-style keys have a satisfying up-and-down movement. Two feet under the keyboard can be flipped out to elevate the rear of the keyboard. There's a handy Function-lock switch on the bottom to change whether the F1 through F12 keys perform as such, or according to their secondary printed functions.
The keyboard offers no other features, such as ports or backlighting. It's a great-quality keyboard for being included with the PC, although it does fall short of some aftermarket models when it comes to features.
On the Workbench
I used recent tower-style workstations we've tested for comparisons with the Z2 Tower G4. This is a potent lot, especially when it comes to CPU power. The Core i9-9900K octa-core chip in our HP will more than meet its match against the 10-core chips in the Corsair One Pro i180 and the Dell Precision 5820.
The Corsair and the Asus ProArt PA90 are odd because, while marketed as workstations, they lack professional-grade Nvidia Quadro or AMD Radeon Pro graphics, instead relying on GeForce RTX-class cards that are normally used for gaming. The Quadro RTX 5000 in the HP is closely related to the GeForce RTX 2080, so it'll be intriguing to see how it measures up to the GeForce RTX 2080 Ti GPUs in our workstation tests.
Productivity, Storage & Media Tests
PCMark 10 and 8 are holistic performance suites developed by the PC benchmark specialists at UL (formerly Futuremark). The PCMark 10 test we run simulates different real-world productivity and content-creation workflows. We use it to assess overall system performance for office-centric tasks such as word processing, spreadsheet jockeying, web browsing, and videoconferencing. The test generates a proprietary numeric score; higher numbers are better. PCMark 8, meanwhile, has a Storage subtest that we use to assess the speed of the system's storage subsystem. This score is also a proprietary numeric score; again, higher numbers are better.
The Z2 Tower G4 delivers an outstanding 7,344-point score in PCMark 10, leaving the competition far behind. (Well, all but the Dell Precision 5820, which is an unknown since it was incompatible with the test.) To be fair to the Asus and Corsair units, it would likely be hard to tell them apart from the HP in the general usage scenarios that PCMark 10 simulates, though. For the PCMark 8 Storage scores, these units all line up around the 5,000-point bar we expect from systems using fast SSD boot storage.
Next is Maxon's CPU-crunching Cinebench R15 test, which is fully threaded to make use of all available processor cores and threads. Cinebench stresses the CPU rather than the GPU to render a complex image. The result is a proprietary score indicating a PC's suitability for processor-intensive workloads.
A score around 2,000 points is the norm for the Core i9-9900K CPU used by the Asus and our Z2 Tower G4. Despite having two fewer cores, it's able to match the performance from the 10-core Dell thanks to its higher clocks. There was no catching the Corsair and its Core i9-9920X, though, a 10-core/20-thread CPU from Intel's higher-end Core X-Series processors that doesn't lack for clock speed.
We also run a custom Adobe Photoshop image-editing benchmark. Using an early 2018 release of the Creative Cloud version of Photoshop, we apply a series of 10 complex filters and effects to a standard JPEG test image. We time each operation and, at the end, add up the total execution time. As with Handbrake, lower times are better here. The Photoshop test stresses CPU, storage subsystem, and RAM, but it can also take advantage of most GPUs to speed up the process of applying filters, so systems with powerful graphics chips or cards may see a boost.
This one is virtually a three-way tie, with the Corsair mopping up the rear in what may have been a bad run for it. There's no doubt all these machines would make short work of any everyday Photoshop task.
Graphics Tests
3DMark measures relative graphics muscle by rendering sequences of highly detailed, gaming-style 3D graphics that emphasize particles and lighting. We run two different 3DMark subtests, Sky Diver and Fire Strike, which are suited to different types of systems. Both are DirectX 11 benchmarks, but Sky Diver is more suited to laptops and midrange PCs, while Fire Strike is more demanding and made for high-end PCs to strut their stuff. The results are proprietary scores.
Next up is another synthetic graphics test, this time from Unigine Corp. Like 3DMark, the Superposition test renders and pans through a detailed 3D scene and measures how the system copes. In this case, it's rendered in the company's eponymous Unigine engine, offering a different 3D workload scenario than 3DMark, and a second opinion on the machine's graphical prowess.
I won't overanalyze these results, since the Z2 Tower G4 and workstations in general aren't geared toward these gaming-centric workloads. However, both 3DMark Fire Strike and Superposition (the latter at the 1080p High setting) give good indications as to the overall 3D performance potential of a PC. The HP and its Quadro RTX 5000 are predictably behind the GeForce RTX 2080 Ti-equipped Corsair, but let's try some workstation tests to see what the Quadro can do.
Workstation-Specific Tests
First up is Cinebench R15, this time using its OpenGL test to exercise the hardware-accelerated rendering capabilities of a GPU.
The only takeaway from these results is that, for this kind of rendering task, the Quadro cards in the HP and the Asus have much better performance than the GeForce card in the Corsair. As to why the Asus and its older Quadro GPU match up to the HP, I can't say for certain, but a CPU bottleneck is a possibility.
Now let's try POV-Ray 3.7, a tool that uses ray tracing to create three-dimensional images. (Note that it doesn't use Nvidia's proprietary RTX ray-tracing features.)
As this is a CPU-dependent test, the Corsair unsurprisingly comes out on top as it did in Cinebench. Unlike Cinebench, however, the high-clocked eight-core CPUs in the Asus and the Z2 Tower G4 are outmatched by the lower-clocked 10-core Dell. More cores aren't always better, but they are in this scenario.
Last, we'll run SPECviewperf 13 to measure graphics performance in some sample professional applications. The three viewsets we run are Creo, Maya, and SolidWorks.
The Maya viewset is a dead heat between the HP and the Corsair, but the HP dominates it in Creo, and takes an even more commanding lead over the Asus in the same test. I don't have comparison numbers for the Corsair in SolidWorks, but the HP shows a good lead over the Asus there, too, which isn't surprising since it has a newer, more powerful GPU. This is where a GPU like the Quadro RTX 5000 comes into its own.
Experimental RTX Testing
The Quadro RTX 5000 GPU in our Z2 Tower G4 has the ray tracing and tensor cores of the GeForce RTX line, yet none of our current workstation tests brings them to bear. I had to give them a go, so I used an experimental version of OctaneBench that rendered one scene. The test results are measured in mega samples per second, and I ran the task with RTX on, and then with it off.
Enabling the RTX features made the renders nearly three times faster, and that's just an average of all the methods used to render it. I'm unsure how this test would run on an equivalent GeForce RTX-class GPU (I intend to experiment more with OctaneBench, as additional relevant hardware passes through), so I can't say whether the Quadro is leaps and bounds in front on this scenario. However, "true" workstation PCs don't usually give the option to configure with non-professional-grade dedicated GPUs (the Z2 Tower G4 doesn't, for one). So, if the software you use can take advantage of the RTX-specific features, the Quadro RTX cards could be an easy upsell.
A Solid Workstation Value
The HP Z2 Tower G4 is a fine choice for a mid-tower desktop workstation. Entry-level it may be by workstation standards, but its nearly endless configurations allow it to be tailored for almost any usage. It's budget-friendly, too, thanks to its availability with Intel Core-class processors that, unlike some Xeon chips, don't require ECC memory. It also offers very high-end GPU options like the Nvidia Quadro RTX 5000 16GB card in our review sample, which is decidedly unlike an entry-level workstation.
That said, the bottomless configuration options for this tower can be their own worst enemy. Despite being well-equipped for just about everything, our test unit missed some basics like USB-C and a flash-card reader. It fortunately wasn't lacking for anything else.
The Z2 Tower G4 in our as-tested guise is powerful, quiet, serviceable, and, for a tricked-out workstation, relatively affordable. A standard three-year onsite warranty on even the least-expensive configuration seals the deal and makes this HP our top pick for a mid-tower workstation.
HP's Z2 Tower G4 measures up to the workstation competition and then some. As tested with an Intel Core i9 CPU and an Nvidia Quadro RTX 5000 GPU, it offers solid performance per dollar and quiet operation, not to mention excellent expansion potential.
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