The ASRock NUC BOX-155H is quite the performer considering its small footprint of 117.5 x 110.0 x 49 mm. While it typically isn't quite as powerful as ASRock's 4X4 BOX-7840U it makes up for this with a few Intel features and software addons that may prove useful depending on the workload or system usage. For example Intel's Quick Sync which enjoys great support in Plex. Then of course you have ASRock's AI Guru software which is built on Intel's OpenVINO toolkit. While I didn't find it fast enough for my usage scenario, which was primarily Face Recognition for going through massive photo libraries, the software offers many more features, such as Object Detection, Human Pose Estimation, Image Inpainting, and more. Depending on the situation these quick and easy to use tools may prove beneficial to some even if they are a bit niche.

When it comes to actual performance the Meteor Lake Core Ultra 7 155H is a bit of a new breed of processor as it offers 6 P-cores, 8 E-cores, and 2 LP E-cores for a total of 16 cores and 22 threads. In Cinebench R20 the system scores 5554 in the multicore test placing it above AMD's 7735U and within striking distance of the 7840U / 7840HS. The same is true in our Blender render test. In our Adobe Premiere Pro Object Tracking test when equipped with enough system memory, it offered the same level of performance as the previously mentioned AMD processors. On the integrated graphics front, Intel's Arc graphics prove to be a viable alternative in many situations to AMD's Radeon 780M. While performance heavily depends on the test, the Arc graphics managed to eke out victories in all the 3DMark graphics tests. This result was repeated in the Unigine Superposition benchmark as well. In actual gaming tests performance isn't quite as good as the AMD Radeon 780M, however, it did deliver playable results. Even at 1080p Native, GTA V and Fallout 4 were playable with minimum frame rates staying well above 30 FPS. In the Witcher 3 performance was also solid, and I would consider Warhammer Total War playable as well. The only game that had issues was Fortnite where the game would exhibit drops to 0 FPS. While the avg frame rate was solid at 88 FPS consistently, drops to 0 every 20–40 seconds mean I would not consider this game playable. Multiple runs and tests exhibited the same behavior. Therefore, while Intel's Arc graphics have more than enough horsepower, the drivers still need more work at least for certain Unreal Engine 5 based titles.

On the power and temperature front the system averages around 15–25 watts during light loads with Idle temperatures hovering around 34°C and moving up to 50°C under said light loads. Moderate loads saw the system pulling 50 watts avg with temperatures reaching 64°C. Finally, extreme loads saw power usage climb to 80 watts when boosting with temperatures hitting 77°C, and once the boost duration ran out the Intel Core Ultra 7 155H drops down to 57 watts with temperatures falling to 67°C. If you want to gain extra performance and understand the risks that come with tuning, the system's performance can be greatly improved using ThrottleStop to boost the TDP values and boost duration. While the cooling can no longer keep up in certain scenarios under extreme loads I was able to improve overall performance, with Cinebench R20 score regularly exceeding 5500 points, sometimes hitting over 6000, up from 4636 (4400-4900 range) in performance mode (which is how we tested) and 3433 in normal mode. However, that increase in performance required the system to pull 80–100 watts, while also hitting its thermal throttle point.

If ASRock offered proper fan control via the BIOS it would be possible to truly have a stellar performer here but like most Mini-PCs the best you can hope for is a target "level" that offers little control if any as the target temperature max is 65°C, after which point the fan ramps up very quickly. A proper PWM curve coupled with performance mode would make this unit really shine. As things are now, if you want a quiet system you will want to stick with normal mode. If you want performance and can handle peak noise levels of 53 dBA (6-inches / 15 cm) then that is the road I would take. Especially if it is going to be mounted to a monitor at which point noise levels at the same distance drop to 48 dBA and at 2ft or 60 cm that noise level drops to 42 dBA. Another option for the brave / experienced is to use ThrottleStop with custom values for the TDP and duration which does allow for a better overall user experience. However, this again could be done without the extra steps if ASRock simply had proper fan control in the BIOS. That said, while the fan can get loud, the noise itself isn't terrible. I didn't notice any odd bearing noises or high-pitched tones. Instead, it's just the sound of air moving.

PS2 emulation showcases solid performance, with only MGS3 presenting occasional challenges, particularly with cutscenes, which is a known and persistent issue. Nonetheless, other titles like Onimusha Dawn of Dreams, Suikoden IV + V, Kessen 1 + 3, ran flawlessly at 1080p, establishing the system as an excellent choice for an emulator station experience. Given the impressive performance of the iGPU in this context, there's potential for it to emulate newer systems effectively.

While build quality is quite good, in terms of I/O, the unit does indeed feel lacking in the number of USB ports it provides. However, the use of a Type-C/Thunderbolt hub would address this issue while still allowing for the use of an eGPU if you need extra performance. In the default configuration with no additional adapters, having only three Type-A ports can feel quite limiting. Yet, in certain situations, this limitation can be compensated for by the inclusion of two Ethernet ports, both of which are 2.5 GbE. Nevertheless, many users may find it necessary to acquire a USB hub if they regularly use multiple USB devices. Storage options are on the other hand a strong suit of the BOX-155H as it offers an M.2 2280/2242 and an M.2 2242 for two high performance storage options alongside a 2.5" SATA drive. The BOX-155H also allows for four displays via the two HDMI 2.1 ports together with using USB Type-C ports for DisplayPort.

Sadly, the biggest negative for the ASRock NUC BOX-155H is the price. At $699.99 barebones and $899.99 as configured it gets outperformed by far more affordable ready to go options. While some of its features may in certain scenarios help offset the higher cost, those only looking at performance will find far more competitive options for a similar or lower budget. Units like the Beelink SER7 7840H with 32 GB of ram and a 1 TB SSD can be had for $739, and I have seen them go on sale regularly for around $600. Essentially meaning you can get better general performance for less while also being fully equipped out of the box. The gap only grows when you consider memory, storage and OS cost, where the Beelink is more affordable with better performance.

Although the ASRock NUC BOX-155H is expensive for an SFF/Mini-PC, it does have potential and can deliver exceptional performance in a tiny form factor along with great versatility, with no issues handling nearly any task you can throw at it. It is also very easy to maintain and work with in regard to upgrades compared to some of its direct competitors. However, its current price means that even with useful software like AI Guru, it is hard to recommend, especially when compared to ASRock's own AMD offerings like the 4X4 BOX-7735U/D5 which offers similar performance but is $160 cheaper barebones vs barebones with both systems trading blows depending on the test. Therefore, while I like what the NUC BOX-155H offers I can't recommend it at the current price, if it was closer to $600 I would likely change my mind.