Introduction and Setup Impressions

Over the last couple of years, mini-PCs in the ultra-compact form factor (UCFF) have emerged as one of the bright spots in the troubled PC market. Zotac is no stranger to this segment. In fact, their nano xs units came to the market before the Intel NUC, even though the NUC is credited with kickstarting the UCFF trend. Intel's Bay Trail family of SoCs has proved to be an affordable and low-power candidate for UCFF PC units. We have already evaluated a couple - the actively cooled GIGABYTE BXBT-1900 and and the fanless ECS LIVA.

The low power nature of the Bay Trail SoCs makes them very amenable to passively cooled systems. Zotac introduced the C-Series passively cooled PCs last year. It also includes a Bay Trail-based unit, the ZBOX CI320 nano. We have already looked at the ZBOX CI540 nano (based on Intel Haswell-Y) and ZBOX CA320 nano (based on AMD Temash) in detail. The build and feature set of the ZBOX CI320 nano are very similar.

Even though we were sampled the barebones version, we took the RAM and SSD from our ZBOX CA320 nano PLUS to get the system up and running. The CI320 nano PLUS is also one of the popular models from Zotac to come with Windows 8.1 Plus Bing - a Microsoft initiative to cut down on licensing costs for OEMs making certain types of computing devices. Bundled with a Windows 8.1 license, the CI320 nano PLUS costs less than $260. This is much cheaper than what one would pay for a Windows 8.1 license if they were to purchase the barebones unit (around $140) and the RAM / SSD separately. The specifications of our Zotac ZBOX CI320 nano review configuration are summarized in the table below.

Zotac ZBOX CI320 nano Specifications
Processor	Intel Celeron N2930 (4C/4T x 1.83 GHz, 22nm, 2MB L2, 7.5W TDP, 4.5W SDP)
Memory	1x 4GB DDR3L-1600
Graphics	Intel HD Graphics
Disk Drive(s)	FORESEE 64 GB 2.5" SSD
Networking	1x Gigabit Ethernet, 1x1 802.11ac/Bluetooth mPCIe
Audio	Capable of 5.1/7.1 digital output with HD audio bitstreaming (HDMI)
Operating System	Retail unit is barebones, but we installed Windows 8.1 Pro x64
Pricing (Win 8.1 Plus Bing)	$257
Full Specifications	Zotac ZBOX CI320 nano PLUS with Windows 8.1 with Bing

Our Zotac ZBOX CI320 nano kit didn't come with any pre-installed OS, but it did have a CD and a read-only USB key containing the drivers. In any case, we ended up installing the latest drivers downloaded off Zotac's product support page. In addition to the main unit, the other components of the package include a 40 W (19V @ 2.1A) adapter, a US power cord, a VESA mount (along with the necessary screws), a single 2.4 GHz / 5 GHz antenna for the Wi-Fi feature, a driver CD / read-only USB key, user's manual and a quick-start guide. The gallery below takes us around the hardware in the unit.

In the table below, we have an overview of the various systems that we are comparing the Zotac ZBOX CI320 nano against. Note that they may not belong to the same market segment. The relevant configuration details of the machines are provided so that readers have an understanding of why some benchmark numbers are skewed for or against the Zotac ZBOX CI320 nano when we come to those sections.

Comparative PC Configurations
Aspect	Zotac ZBOX CI320 nano	Zotac ZBOX CI320 nanoIntel D54250WYKHGIGABYTE GB-BXBT-1900GIGABYTE GB-BXi7-4500Zotac ZBOX CI540 nanoZotac ZBOX OI520 PlusZotac ZBOX CA320 nanoECS LIVA
CPU	Intel Celeron N2930	Intel Celeron N2930
GPU	Intel HD Graphics	Intel HD Graphics
RAM	Crucial CT51264BF160B (Micron 8KTF51264HZ-1G6J1) 11-11-11-28 @ 1600 MHz 1x4 GB	Crucial CT51264BF160B (Micron 8KTF51264HZ-1G6J1) 11-11-11-28 @ 1600 MHz 1x4 GB
Storage	FORESEE S600S064G (64 GB; 2.5in SATA 6Gb/s; MLC)	FORESEE S600S064G (64 GB; 2.5in SATA 6Gb/s; MLC)
Wi-Fi	Intel Dual Band Wireless-AC 3160 (1x1 802.11ac - 433 Mbps)	Intel Dual Band Wireless-AC 3160 (1x1 802.11ac - 433 Mbps)
Price (in USD, when built, no OS)	$240	$240

Performance Metrics - I

The Zotac ZBOX CI320 nano was evaluated using our standard test suite for low power desktops / industrial PCs. We revamped our benchmark suite earlier this year after the publication of the Intel D54250WYK NUC review. We reran some of the new benchmarks on the older PCs also, but some of them couldn't be run on loaner samples. Therefore, the list of PCs in each graph might not be the same.

Futuremark PCMark 8

PCMark 8 provides various usage scenarios (home, creative and work) and offers ways to benchmark both baseline (CPU-only) as well as OpenCL accelerated (CPU + GPU) performance. We benchmarked select PCs for the OpenCL accelerated performance in all three usage scenarios. These scores are heavily influenced by the CPU in the system. The Ceneron N2930 in the CI320 nano is not as powerful as the Haswell-Y Core i4 in the CI540 nano or the Haswell-U CPUs in the NUCs with similar form factor. However, those PCs are either much costlier or require fans for cooling.

Miscellaneous Futuremark Benchmarks

3D Rendering - CINEBENCH R15

We have moved on from R11.5 to R15 for 3D rendering evaluation. CINEBENCH R15 provides three benchmark modes - OpenGL, single threaded and multi-threaded. Evaluation of select PCs in all three modes provided us the following results.

Benchmarks which rely on GPU performance are won by the AMD Temash-based ZBOX CA320 nano, while those relying on CPU performance (either single or multi-threaded) are won by the ZBOX CI320 nano. The ECS LIVA lags both of these, but it does come at a lower price point.

Performance Metrics - II

In this section, we mainly look at benchmark modes in programs used on a day-to-day basis, i.e, application performance and not synthetic workloads.

x264 Benchmark

First off, we have some video encoding benchmarks courtesy of x264 HD Benchmark v5.0. This is simply a test of CPU performance. As expected, the Celeron N2930 at 1.83 GHz manages to surpass the N2806 (at 1.6 GHz) in the ECS LIVA as well as the AMD A6-1450 in the CA320 nano. It does lose out to the actively-cooled 2.41 GHz Celeron J1900 in the GIGABYTE GB-BXBT-1900.

7-Zip

7-Zip is a very effective and efficient compression program, often beating out OpenCL accelerated commercial programs in benchmarks even while using just the CPU power. 7-Zip has a benchmarking program that provides tons of details regarding the underlying CPU's efficiency. In this subsection, we are interested in the compression and decompression MIPS ratings when utilizing all the available threads.

TrueCrypt

As businesses (and even home consumers) become more security conscious, the importance of encryption can't be overstated. CPUs supporting the AES-NI instruction for accelerating the encryption and decryption processes have, till now, been the higher end SKUs. However, with Bay Trail, even the lowly Atom series has gained support for AES-NI. Unfortunately, the Celeron N2930 SKU doesn't support AES-NI. TrueCrypt, a popular open-source disk encryption program can take advantage of the AES-NI capabilities. The TrueCrypt internal benchmark provides some interesting cryptography-related numbers to ponder. In the graph below, we can get an idea of how fast a TrueCrypt volume would behave in the Zotac ZBOX CI320 nano and how it would compare with other select PCs. This is a purely CPU feature / clock speed based test.

Agisoft Photoscan

Agisoft PhotoScan is a commercial program that converts 2D images into 3D point maps, meshes and textures. The program designers sent us a command line version in order to evaluate the efficiency of various systems that go under our review scanner. The command line version has two benchmark modes, one using the CPU and the other using both the CPU and GPU (via OpenCL). The benchmark takes around 50 photographs and does four stages of computation:

• Stage 1: Align Photographs
• Stage 2: Build Point Cloud (capable of OpenCL acceleration)
• Stage 3: Build Mesh
• Stage 4: Build Textures

We record the time taken for each stage. Since various elements of the software are single threaded, others multithreaded, and some use GPUs, it is interesting to record the effects of CPU generations, speeds, number of cores, DRAM parameters and the GPU using this software.

Dolphin Emulator

Wrapping up our application benchmark numbers is the Dolphin Emulator benchmark mode results. This is again a test of the CPU capabilities.

Networking and Storage Performance

We have recently started devoting a separate section to analyze the storage and networking credentials of the units under review. On the storage side, one option would be repetition of our strenuous SSD review tests on the drive(s) in the PC. Fortunately, to avoid that overkill, PCMark 8 has a storage bench where certain common workloads such as loading games and document processing are replayed on the target drive. Results are presented in two forms, one being a benchmark number and the other, a bandwidth figure. We ran the PCMark 8 storage bench on selected PCs and the results are presented below.

Given that we were using the same SSD in the both the CA320 nano and CI320 nano, the storage benchmark numbers are not surprising. The CI320 nano does show a decrease in the storage bandwidth - this leads us to believe that the FORESEE SSD is not that great at maintaining performance consistency in the long run. That said, a 64 GB SSD is really cutting things close when it comes to a full-blown Windows installation and a large number of installed benchmarking programs and test videos.

On the networking side, we restricted ourselves to the evaluation of the WLAN component. Our standard test router is the Netgear R7000 Nighthawk configured with both 2.4 GHz and 5 GHz networks. The router is placed approximately 20 ft. away, separated by a drywall (as in a typical US building). A wired client (Zotac ID89-Plus) is connected to the R7000 and serves as one endpoint for iPerf evaluation. The PC under test is made to connect to either the 5 GHz (preferred) or 2.4 GHz SSID and iPerf tests are conducted for both TCP and UDP transfers. It is ensured that the PC under test is the only wireless client for the Netgear R7000. We evaluate total throughput for up to 32 simultaneous TCP connections using iPerf and present the highest number in the graph below.

In the UDP case, we try to transfer data at the highest rate possible for which we get less than 1% packet loss.

Again, the results are similar to the CA320 nano - all the C-series units use the same WLAN chips from Intel. The performance is a bit better, possibly due to the faster and more efficient CPU in the CI320 nano.

HTPC Credentials

The absence of any moving parts inside the ZBOX CI320 nano enables a completely silent PC irrespective of the workload. This makes it an ideal HTPC. While acoustics form one part of the HTPC story, there are a few other aspects that we will cover in this section.

Refresh Rate Accurancy

AMD and NVIDIA have historically been able to provide fine-grained control over display refresh rates. The default rates are also quite accurate. Intel used to have an issue with 23 Hz (23.976 Hz, to be more accurate) support, but that was resolved with the introduction of Haswell and Bay Trail. As expected, the Zotac ZBOX CI320 nano has no trouble with refreshing the display appropriately in the 23 Hz setting.

The gallery below presents some of the other refresh rates that we tested out. The first statistic in madVR's OSD indicates the display refresh rate.

Network Streaming Efficiency

Evaluation of OTT playback efficiency was done by playing back our standard YouTube test stream and five minutes from our standard Netflix test title. Using HTML5, the YouTube stream plays back a 720p encoding, while Adobe Flash delivers a 1080p stream. Note that only NVIDIA exposes GPU and VPU loads separately. Both Intel and AMD bundle the decoder load along with the GPU load. The following two graphs show the power consumption at the wall for playback of the HTML5 stream and the Adobe Flash stream in Mozilla Firefox (v 33.1.1). The Flash plugin version used for benchmarking was 15.0.0.223. GPU load was around 33.05% for the HTML5 stream and 22.53% for the Flash stream.

Netflix streaming evaluation was done using the Windows 8.1 Netflix app. Manual stream selection is available (Ctrl-Alt-Shift-S) and debug information / statistics can also be viewed (Ctrl-Alt-Shift-D). Statistics collected for the YouTube streaming experiment were also collected here. GPU load in the steady state for the Netflix streaming case was 3.58%.

Decoding and Rendering Benchmarks

It is quite clear that passively cooled UCFF PCs such as the CI320 nano are not madVR-capable machines. Hence, we concentrate on local file playback using EVR-CP and Kodi. The decoder used was LAV Filters bundled with MPC-HC v1.7.7

Zotac ZBOX CI320 nano - Decoding & Rendering Performance
Stream	EVR-CP		XBMC
	GPU Load (%)	Power (W)	GPU Load (%)	Power (W)
480i60 MPEG2	49.20	10.52	30.05	9.50
576i50 H264	46.29	10.24	55.29	10.29
720p60 H264	58.11	11.84	65.46	10.81
1080i60 MPEG2	80.57	14.35	74.47	13.61
1080i60 H264	89.04	15.08	81.13	14.18
1080i60 VC1	86.21	14.84	78.87	13.98
1080p60 H264	76.08	13.22	71.10	11.32
1080p24 H264	33.03	10.11	28.43	9.50
4Kp30 H264	80.09	13.97	44.65	11.14

The CI320 nano was able to pass all our test streams using decoders / renderers that the average consumer would use. Even the 4Kp30 H.264 stream decoded without frame drops and was output on to a 1080p display without issues. The only caveat is that HD audio bitstreaming is not enabled on these Bay Trail boxes under Windows, but works without issues in Linux. On a side note, this doesn't affect Dolby Digital Plus bitstreaming from the Netflix app. In our opinion, this would make a great little OpenELEC box or Ubuntu / XBMC system.

Power Consumption and Thermal Performance

The power consumption at the wall was measured with a 1080p display being driven through the HDMI port. In the graphs below, we compare the idle and load power of the Zotac ZBOX CI320 nano with other low power PCs evaluated before. For load power consumption, we ran Furmark 1.12.0 and Prime95 v27.9 together. The numbers are not beyond the realm of reason for the combination of hardware components in the machine.

Reasonable power aside, there does seem to be a BIOS default configuration issue causing the idle power to be a bit on the high end. One of the possible reasons was revealed in our evaluation of the thermal performance (discussed below).

The various clocks in the system as well as the temperatures within the unit are presented below. We start with the system at idle, followed by 30 minutes of pure CPU loading. This is followed by another 30 minutes of both CPU and GPU being loaded simultaneously. After this, the CPU load was removed, allowing the GPU to be loaded alone for another 30 minutes.

A look at the frequencies above indicates that all the cores are pegged at 1.83 GHz throughout our evaluation (even at idle). On the other hand, the GPU frequency varies between 600 and 800 MHz depending on the GPU load. The junction temperature of the Celeron N2930 is 100 C. The cooling system is efficient and manages to keep the SoC temperature below 93 C even under extreme duress.

Another important aspect to keep note of while evaluating fanless PCs is the chassis temperature. Using Seek Thermal's thermal imager, we observed the chassis temperature after the CPU package temperature reached the steady state value in the above graph.

Surprisingly, the chassis temperature was less than 70 C even after heavy loading. Though this is not as low as the 56 C we observed in the CA320 nano, it is better than the 75 C+ that we saw in the CI540 nano.

Final Words

The Zotac ZBOX CI320 nano provided us with an opportunity to evaluate one of the more configurable, but passively cooled Bay Trail UCFF PCs in the market. Passively cooled systems are either very costly (particularly if they integrate powerful CPUs) or downright abysmal in performance (when they integrate the low-end / low-power CPUs such as the older Atoms). Zotac's offering with the ZBOX CI320 nano aims to strike a balance. $140 for a barebones configuration is quite good in this market segment. A fully loaded PLUS model, along with a pre-installed licensed version of Windows 8.1 is lesser than $260. It is frankly quite difficult to build such a compact and passively cooled system for that price on one's own.

One of the aspects we were worried about was thermal throttling, but the ZBOX CI320 nano surpassed our expectations. The chassis never got extremely hot (reaching only around 68 C, even after extended thermal stress with a couple of power viruses).

Pretty much the only downside of the unit is the relatively bad performance of Bay Trail when compared to Haswell. However, we shouldn't be really complaining for the price since the system seems to operate quite nicely for day-to-day use. The BIOS does need some work - particularly to ensure that cores are not in the max performance mode always in the default configuration. The SSD supplied with the PLUS model could be a bit better, but that is not an issue if the end-user buys a barebones configuration.

All in all, Zotac manages to deliver a very price-effective passive mini-PC in the ZBOX CI320 nano. Along with the ECS LIVA and the Zotac ZBOX CA320 nano in the market, the days of users having to spend an arm and leg for passively cooled systems with decent performance are history.