ASRock Industrial 4X4 BOX-7840U mini-PC Review: AMD Phoenix in an UCFF Avatar

ASRock Industrial has been one of the most prolific vendors in the ultra-compact form-factor (UCFF) PC space over the last few years. They have been releasing 4"x4" systems based on the latest AMD and Intel platforms within a few weeks of their announcements by the processor vendors. On the AMD front, the company released the Rembrandt Refresh-based 4X4 BOX-7735U earlier this year, and followed that up a couple of quarters later with the Phoenix-based 4X4 BOX-7040 series.

The 4X4 BOX-7040 series builds upon the I/O and iGPU improvements in the 4X4 BOX-7735U with the incorporation of AMD's latest Zen 4 CPU cores and RDNA3-based iGPU. The move to a 4nm TSMC process (from the 6nm one used for Rembrandt Refresh) and the CPU / iGPU improvements should theoretically delivery much better performance and power efficiency for a range of workloads.

The Ryzen 7 7840U is a 28W TDP part that bears striking similarity to the Ryzen 7 7840HS that was already evaluated in a 65W mode in Beelink's GTR7. As a result of the lower power limit, the base clock is lowered. The iGPU configuration, I/Os, and other operating parameters remain the same. The U-series is primarily meant for notebook platforms, but ASRock Industrial (and other mini-PC vendors) have been deploying them in actively-cooled UCFF cases. The presence of a fan gives vendors a bit of leeway in configuring the power limits - and, as an extension, performance.

ASRock Industrial ships the 4X4 BOX-7840U in the 'Normal Mode' with AMD's suggested TDP of 28W. However, a toggle in the BIOS can push the system into a 'Performance Mode' with a souped-up TDP of around 40W. This review explores the performance profile of the PC in both modes, and provides detailed insights into the differentiating aspects of AMD's Phoenix in a UCFF mini-PC platform.

Introduction and Product Impressions

UCFF systems have been steadily replacing bulky tower desktops for many use-cases over the last decade. This category has been experiencing growth in both home consumer and industrial settings, with the latter prompting the B2B / industrial computing arms of many motherboard vendors to provide more attention to such systems. ASRock Industrial (spun out of ASRock's business unit in 2018) has been creating UCFF systems based on both AMD and Intel platforms since 2019.

This review delves in detail into the company's AMD Phoenix-based flagship UCFF offering - the 4X4 BOX-7840U. Based on AMD's high-end Phoenix 28W offering (Ryzen 7 7840U), the new system is meant to be a follow-up to the Rembrandt-R-based 4X4 BOX-7735U released earlier this year. The Ryzen 7 7840U continues with the same 8C/16T configuration of the Ryzen 7 7735U. However, the fabrication process has moved from TSMC's 6nm FinFET to 4nm FinFET, and the CPU cores are now based on Zen 4. The integrated GPU has also been re-architected, moving from the RDNA2-based Radeon 680M in Rembrandt-R to the RDNA3-based 780M in Phoenix.

ASRock Industrial's UCFF systems are non-descript machines that do not opt for a fancy case design. The functional chassis used in previous 4X4 BOX systems is retained for the 4X4 BOX-7840U also. This does mean an extension of the lifespan of the glossy polycarbonate fingerprint magnet casing, but that is set to change in 2024. The I/O port locations are exactly the same as in the previous generation. The internal board is also largely the same, as the USB4 ports and DDR5 support were already pencilled in during the design of the 4X4 BOX-7735U.

The company's 4X4 BOX-7040 series has only two members - one based on the Ryzen 5 7640U and the other based on the Ryzen 7 7840U. Some of the key relevant aspects are brought out in AMD's introductory slide to the product family back at the 2023 CES.

ASRock Industrial's choice of I/O ports for the Intel and AMD systems in the same generation is worth a note. While the rear USB ports are only USB 2.0 in the AMD ones, they are USB 3.2 Gen 2 in the Intel versions. However, the two front panel Type-C ports support the full USB4 feature set including PCIe tunneling in the AMD systems. The Intel boards are skimped on, with only one of the Type-C ports capable of full USB4 / Thunderbolt 4 support and the other falling back to USB 3.2 Gen 2 with Alt DP support.

The company offers both barebones version of the system as well as the motherboard alone. The former is typically sold in retail, while the motherboard is meant for the B2B channel. The barebones version package comes with a 120W DC power adapter (19V @ 6.32A), VESA mount (and associated screws), a geo-specific power cord, the main unit, and a product overview / user guide.

The barebones version needs two DDR5 SODIMMs and a M.2 2280 SSD to complete the build. Crucial's DDR5-5600 SODIMM kit (2x16GB) was complemented by a Samsung 990 PRO 2TB Gen 4 NVMe SSD for this purpose.

Access to the SODIMM and M.2 slots is via the underside, similar to the previous generation systems. Removal of the four screws at the bottom allows the panel to be popped off.

Despite the support for a 2.5" SATA drive in the system, ASRock Industrial strongly recommends not using it in order to aid with proper airflow. The installation process is otherwise similar to the older 4X4 BOX systems, and we were up and running with a freshly installed OS in no time (after installing the chipset drivers from the product support page). The Ryzen 7 7840U does include the XDNA engine (now rebranded as Ryzen AI in Phoenix Refresh), but the drivers for that (recognized as an IPU in Device Manager) are not yet available through Windows Update.

The full specifications of the review sample (as tested) are provided in the table below. As we will note in the next section, the BIOS allows the system to be configured in either of two modes with different TDPs, as specified in the Processor entry.

In the next section, we take a look at the system setup and follow it up with a detailed platform analysis.