Asus’ ROG Maximus VI Impact Mini-ITX motherboard reviewed

Mini-ITX motherboards have come a long way since their humble beginnings. The 6.7″ x 6.7″ form factor was introduced as a vessel for low-power Via processors that were suitable for only the most basic of computing tasks. People liked the smaller footprint, and before long, Mini-ITX boards started sporting the same sockets as full-sized ATX mobos. These diminutive desktop boards were somewhat obscure at first, but they’ve slowly become a staple of every major motherboard maker’s lineup.

Most Mini-ITX boards still stick to the budget end of the spectrum. We’ve seen more and more enthusiast-oriented designs in recent years, though. Some of them, like Asus’ Maximus VI Impact, even reach into premium territory.

Now, this is the point where some of our more frugal readers may be tempted to tune out. High-end mobos are typically no faster than cheaper alternatives, and their upgraded peripherals and fancy extras rarely justify their higher asking prices. Bear with me, though, because Mini-ITX boards have limited expansion potential; their integrated peripherals are therefore much more valuable than they would be a on a board with room for add-in cards. The ITX form factor presents some other challenges that a premium board like this one can help to overcome, as well.

The Maximus VI Impact looks promising on all fronts. Its integrated audio circuitry lives on a separate riser card that’s isolated from board-level noise. Next to that riser sits a separate module with 802.11ac Wi-Fi and Bluetooth connectivity alongside an M.2 slot for mini SSDs. On top of those perks, the board and box are littered with thoughtful little extras that are particularly well-suited to Mini-ITX builds.

The Impact isn’t all that expensive, either. I wouldn’t call the $220 asking price cheap, of course, but it’s much lower than the sticker attached to a lot of flagship Haswell motherboards. So you can see why we’ve been itching to give the Impact a closer look.

Getting acquainted
The first thing one notices when opening the Impact’s box is that the Supreme FX audio riser and mPCIe Combo module are packaged separately. Some assembly is required.

Fortunately, the two components are easy enough to install. Both plug into onboard headers, and their unique pin configurations should ensure that folks use the right ones. Once attached, the modules are held firmly in place by screws.

The assembly process shouldn’t intimidate folks who have already committed to assembling a PC from scratch. I’m a little surprised the add-ons aren’t installed at the factory, though. Asus probably wants to avoid potential damage during shipping. Having the parts separate at least makes it easier to get a closer look at them, which we’ll do in a moment. Before that, we should address the third riser card, which comes pre-installed.

Premium motherboards typically have elaborate power regulation circuitry feeding the CPU. Mini-ITX dimensions leave little room around the socket for that circuitry, so the Asus has put it on a separate board that rises up from the Impact’s top edge. This piece hosts an 8+2 phase power delivery complex powered by digital PWMs and cooled by a slim heatsink. Higher-grade electrical components are found not only on the power riser, but also throughout the rest of the board.

The Impact’s trio of vertical elements complicates clearances somewhat. So does the fact that the board is designed for Mini-ITX enclosures. Here’s where the socket sits relative to various landmarks and the edges of the PCB.

Note the decent-sized gap between the CPU socket and the PCI Express slot. The other potential obstructions are much closer to the socket, and there are plenty of them. Thankfully, most of them are relatively short.

The vertical battery mount should be a non-issue, leaving the audio and power risers as the most likely sources of conflict. Those pieces are large enough to interfere with CPU coolers that branch out from the socket. They also cramp the area around the heatsink retention holes, making cooler installation somewhat more difficult for those of us with stubby, clumsy fingers.

Despite its tighter clearances, the Impact can still accommodate a wide range of memory modules, heatsinks, and liquid-cooling gear. It’s also equipped to host the latest and greatest Haswell CPUs, including the recent refresh. Thanks to its top-of-the-line Z87 Express chipset, the Impact is primed to overclock Intel K-series CPUs.

Haswell’s integrated PCIe controller gives the Impact enough Gen3 lanes to fuel a single x16 slot for discrete graphics cards. Two full-sized DIMM slots tap the CPU’s dual memory channels, and four 6Gbps SATA ports hook into the Z87 chipset. To the right, a USB 3.0 header provides a pair of SuperSpeed ports for front-panel connectors. These ports are joined by four more in the rear cluster, which also houses another four USB 2.0 jacks.

There are more ports, of course, including DisplayPort and HDMI video outs and an eSATA connector for older external drives. Plenty of other motherboards offer those extras, but they don’t have the Impact’s cluster-mounted POST code display.

The diagnostic display is joined by a handful of buttons that control various functions. One button clears the CMOS, while another causes the board to boot directly into the firmware. Switches are also provided for ROG Connect, Asus’ remote tweaking interface, and MemOK!, a feature that cycles through different memory profiles for finicky DIMMs. Having these functions accessible outside the case is a huge bonus for Mini-ITX systems, whose internals are often too crowded to poke around inside easily.

Of all the Impact’s cluster-mounted goodies, the S/PDIF audio output is among the most important. This port passes pristine digital bitstreams to compatible speakers and receivers, neatly bypassing the pitfalls associated with onboard analog audio. The digital out natively supports stereo playback and surround-sound sources with pre-encoded tracks, such as movies. DTS Connect software adds on-the-fly encoding for multi-channel output, allowing surround-sound game audio to be piped through the S/PDIF out, as well.

The robust digital output implementation is only one element of the Impact’s integrated audio, of course. On the next page, we’ll take a closer look at the SupremeFX card that handles analog signals.

Add-on integrated audio
Digital audio outputs tend to deliver crystal clear sound quality regardless of whether they’re attached to discrete sound cards or integrated motherboard solutions. Analog sound quality is typically much better on discrete sound cards than in onboard implementations, though. Stand-alone cards can dedicate more board real estate and components to their audio circuitry. They also elevate everything off the surface of the motherboard, separating sensitive analog signals from potential sources of interference.

Mini-ITX boards have only one full-sized expansion slot, forcing users to choose between discrete graphics and sound cards. Audio usually ends up on the losing end of that battle, and the Maximus VI Impact doesn’t change that dynamic. However, the board does elevate its integrated audio to another level via the SupremeFX riser card.

This mini sound module is a sort of cross between the discrete and integrated approaches. It uses a Realtek ALC1150 codec familiar from traditional motherboard audio configs. The chip sits on a riser card instead of the motherboard, though, separating it from board-level noise. The codec is also covered by a separate EMI shield that provides an additional layer of protection.

In a bid to further improve sound quality, the SupremeFX module employs a “dual-differential” circuit design that splits audio signals from the codec into two separate streams. The second stream is the inverse of the first, and the two are recombined by amplifier chips using a process that’s supposed to filter out noise and interference. There are four Texas Instruments LM4562 amplifiers on the riser: three for the analog jacks at the rear, plus one more for the front-panel headphone connector. These amps are rated for headphones up to 600 Ω, which covers most common audio headgear.

Asus claims the SupremeFX riser has a signal-to-noise ratio of 115 dB for the rear outputs and 110 dB for the front headphone jack. Those figures seem impressive, but they reveal little about how the audio actually sounds. To get a better sense of that, I spent an afternoon listening to music on the Impact and a couple of alternatives: the more traditional integrated audio offered by Asus’ X79 Deluxe ATX motherboard and our favorite discrete solution, Asus’ Xonar DSX sound card. These tests were conducted with the rear analog outputs, Sennheiser HD 555 headphones, and normalized volume levels. The playlist included tracks from Adele, Die Antwoord, The Heavy, LCD Soundsystem, and The Tea Party.

To my ears, the Maximus VI Impact’s integrated audio sounds noticeably better than that of the X79 Deluxe. The highs are crisper, the bass is smoother, and the individual elements of each track come through more clearly. Foreground elements pack a harder punch than they do on the Deluxe, and subtler notes don’t get lost in the background. The difference isn’t night and day, but all the little improvements add up to produce a livelier, more detailed sound than typical motherboard audio.

Although the Impact’s SupremeFX audio is a definite improvement over the integrated norm, it’s not on the same level as a good discrete sound card. The Xonar DSX exposes even more subtlety in each track. It has greater range in the middle of the spectrum and a more balanced acoustic profile overall. The Xonar also boasts a more natural sound, without the over-sharpened highs and over-emphasized bass that creeps into the Impact’s output.

For me, the difference between the Xonar and the Impact is bigger than the delta between the two integrated solutions. The Impact still offers an enjoyable listening experience, though. It definitely has better analog output quality than any other Mini-ITX board I’ve tested.

In addition to evaluating audio performance with subjective listening tests, we measured signal quality objectively using RightMark Audio Analyzer. We ran the same three audio implementations through RMAA’s “loopback” test, which pipes audio from the front-channel output through the line input. This test was configured to use high-definition audio with 24 bits of resolution at 96kHz. RMAA ranks subjects in a range of categories using a six-point scale between “very poor” and “excellent.” We’ve converted those results to a numerical scale between a low of one and a high of six.

	Frequency response	Noise level	Dynamic range	THD distortion	THD + noise	IMD + noise	Stereo crosstalk	IMD at 10kHz	Overall score
Maximus VI Impact	5	6	6	5	3	4	6	5	5
X79 Deluxe	6	5	5	5	4	5	6	5	5
Xonar DSX	6	6	6	6	6	6	6	6	6

Surprisingly, the X79 Deluxe outscores the Maximus VI Impact in a few RMAA metrics. The two boards have the same overall rating, though. Both are beaten soundly by the Xonar, which ranks as “excellent” across the board.

We can get a better sense of how the Impact measures up by examining the raw RMAA data. Here are some comparison graphs for several key RMAA metrics. Click the buttons below to switch between them.

The Impact clearly has a narrower frequency response than the Xonar. It also exhibits more crosstalk, noise, and interference than the DSX across the full range of frequencies. Decent discrete sound cards are really in another league.

Versus the X79 Deluxe, the Impact looks a little better. The SupremeFX signal has less noise and interference across most of the spectrum, though it doesn’t fall off like the Deluxe does at extremely high frequencies. That drop-off may be responsible for the Deluxe’s higher scores on our numerical scale.

The RMAA results above were obtained with the systems idling at the Windows desktop. We also ran the same tests while the machines were crunching a combined CPU, GPU, and USB load. RMAA didn’t detect any differences in signal quality, and I didn’t hear any feedback or buzzing in the line.

We’re not done with the integrated audio yet. The Impact has a couple of other tricks up its sleeve, including the ability to pass signals from the front-panel input to the rear output when the system is turned off. Then there’s Sonic Radar, an Asus-developed application that provides a visual representation of surround-sound game audio. Allow me to illustrate:

The overlay on the gun is the Sonic Radar display. It’s highly configurable, with adjustable opacity, size, and positioning. There are different filtering modes, too, allowing one to focus on specific kinds of sounds or all those deemed as threats. These settings can be altered not only through the configuration utility, but also via hotkeys.

Sonic Radar works surprisingly well. The visual display accurately maps in-game audio with no apparent latency. However, I don’t find it terribly useful, mostly because looking at the overlay distracts from the action. For me, listening for audible cues is much easier. The software is optional, of course, so you don’t have to use it.

Speaking of optional, let’s move on to the Impact’s second add-on module…

Fancy networking and extra goodies
Behold the mPCIe Combo II module, which hosts a Mini-PCIe slot for the Impact’s wireless card and an M.2 slot for mini SSDs:

Awww, isn’t it cute? The M.2 slot is easily the most intriguing element of the module. It’s compatible with both PCI Express and Serial ATA-based M.2 drives up to 110 mm long. The slot is limited to a single Gen2 PCIe lane, though. Throughput is effectively capped at 500MB/s in each direction, which means PCIe drives won’t be outrunning the fastest SATA SSDs. Full-fat M.2 slots with dual PCIe lanes have been spotted on next-gen Intel boards.

The prospect of faster SSDs is exciting, but the payoff may be difficult to detect. Even Intel concedes that interface speeds above SATA’s current 6Gbps ceiling have little benefit for typical desktop applications. For the Impact, the M.2 slot’s real appeal is the ability to add a decent SSD directly to the motherboard. That’s a nice bonus for small-form-factor systems with limited drive bays and tricky cable routing.

The Mini PCIe side of the dual-slot module is filled with an Atheros card that supports both 802.11ac Wi-Fi and Bluetooth 4.0. The card is removable, so it can be swapped out for another mPCIe device. It also comes with a two-piece antenna cable that can be routed through the rear I/O panel or the walls of a case. Some drilling may be required for the latter route.

On the wired networking front, the Impact combines an Intel Gigabit Ethernet NIC with GameFirst II traffic management software. This software’s EZ interface is straightforward, with several modes configured to prioritize different kinds of applications. A more advanced UI is available for fine tuning, as well, but the default config worked well for my quick gaming tests, which combined a 1.8MB/s BitTorrent download with a couple of first-person shooters. Battlefield 4 and Counter-Strike: Global Offensive both played smoothly with BitTorrent running in the background; ping times were around 50-70 milliseconds in BF4 and 25-30 ms in CS: Go. They weren’t much lower with GameFirst disabled, which makes me wonder if the software is really necessary. Ping times were low even with the software completely uninstalled, suggesting the Intel driver is smart enough to sling packets on its own.

The GameFirst software is still a nice touch, and there may be scenarios where it impacts network performance in noticeable ways. I can’t help but think the larger source of potential conflict lies higher up the chain, though. Typical homes now host a range of wireless devices in addition to whatever other PCs occupy the network. Quality of service should really be handled by the router, which can manage traffic from all potential sources of contention.

Little extras largely define the Maximus VI Impact. Some of the subtler ones have the biggest effect on the system building process. Take the power connectors, for example. They’re neatly lined up next to each other along one edge, which should simplify cable routing in cramped enclosures.

The onboard power and reset buttons aren’t strictly necessary for most folks, but they do come in handy when the board is running out in the open. Cases provide their own buttons, of course. Hooking them up can be cumbersome even in full-sized desktop systems, so cramped Mini-ITX cases are a potential nightmare. The Impact’s solution to this problem is even slicker than a connector block; it’s a full-on wiring harness.

Yeah, that’s pretty awesome. The Impact also comes with stick-on labels for SATA cables. A cushy I/O shield is in the box, too.

This soft-backed piece lacks the little slivers of metal that protrude from typical I/O panels, reducing the risk of an inadvertent blood sacrifice. The cushioned shield also eliminates the chances of those pokey bits getting caught in the port cluster during motherboard installation.

Such thoughtful refinements aren’t just confined to the Maximus VI Impact’s hardware, either. The same attention to detail is found in the firmware and software, which we’ll explore on the next page.

Firmware and software interfaces
Asus motherboards have some of the best firmware interfaces around. The Impact is no exception; its UEFI is largely similar to what’s found on Asus’ standard 8-series motherboards, just with different colors and a few extras. One of those extras is an integrated secure erase tool:

This tool empties all of the SSD’s flash blocks, putting the drive into its highest-performance state. It’s great for benchmarking, and I’d love to have the capability integrated into the firmware of our storage test rigs. Keep in mind that secure erasing wipes all user data, though. Most PC users will only need to secure-erase drives when setting up a new system or reinstalling their operating system.

In addition to its specialized SSD tool, the UEFI boasts the usual array of overclocking and tweaking options. It also has a bunch of esoteric tweaking settings not typically found on more pedestrian motherboards. These options are largely confined to a “Tweaker’s Paradise” section of the firmware, and most of them are way over my head. I didn’t even know “termination anti-aliasing” was a thing.

The extras settings are nice, but the underlying foundation is what makes the firmware really great. The interface is easy to navigate, the cursor tracking is perfectly smooth, and the options are laid out intelligently. Frequent tuners can customize a special panel with their favorite options from anywhere in the firmware. There are configurable shortcuts, too, plus a separate EZ interface with fewer options and more graphical flair.

The firmware isn’t perfect, of course. I’ve been spoiled by the 1080p resolution of Gigabyte’s 8-series UEFI, so Asus’ standard-def GUI looks a little lo-fi. The firmware engages in illicit overclocking, too. The CPU multiplier is set to “sync all cores” mode by default, which causes the Core i7-4770K to run 200MHz faster than stock when all its cores are engaged. Most systems should be able to handle the higher frequency without issue, but I don’t like the behavior. Motherboard firmware should never overclock the CPU without the user’s permission—and certainly not as part of the default configuration.

Asus contends Republic of Gamers boards like the Maximus VI Impact are aimed at a performance-oriented crowd that wants this sneaky overclocking feature enabled. If you ask me, it’s all about gaining a little bit of an edge in benchmarks. Most motherboard makers engage in similar trickery, and they’ve all been doing it for ages. Fortunately, the Impact behaves normally if the core ratio setting is changed to “auto.”

I’m inclined to forgive the Impact’s few firmware transgressions because of all the other goodness packed into the UEFI. Again, it’s the little things, like having three distinctly different ways to apply extra voltage to the CPU. Configuration changes are logged and displayed upon exiting the firmware, providing a quick confirmation of what’s been modified during the session. Users can save text notes directly to the firmware. The fan controls are pretty flexible, too.

Temperature-based fan speed control is available for all four onboard headers. The options are relatively basic, but they’re still better than what’s available on most other motherboards. They’re also complemented by more robust fan controls in Asus’ AI Suite software for Windows.

This motherboard tuning utility is the best I’ve used. Its fan controls are especially robust, with click-and-drag speed profiles that allow precise fine-tuning. Spin-up and spin-down times can be configured separately, allowing users to control how quickly the fans respond to changes in temperature. There’s also a calibration function that gauges the actual speed range of connected spinners.

In addition to robust fan controls, AI Suite is loaded with overclocking options, power tuning functions, and system monitoring readouts. The options provide enough depth for most tuning endeavors, and newbies should be able to find their way around without too much trouble. The interface is laid out intelligently and skinned beautifully. Asus simply has the best motherboard software around.

Overclocking
The firmware and software both feature automated overclocking schemes. However, they rely on preset profiles rather than the iterative auto-tuner available with Asus’ standard 8-series boards. The company tells us the audience for ROG boards typically prefers to overclock manually, making smarter auto-tuning less critical.

With our Core i7-4770K, pre-tuned profiles are available for 4.2, 4.4, and 4.6GHz. They all employ higher Turbo multipliers to hit those speeds, and the multipliers are applied across all cores evenly. Even the most aggressive profile limits the CPU voltage to 1.3V, which is a sensible ceiling for Haswell.

To test the Impact’s overclocking chops, I kicked our Corsair H80 water cooler into high gear and went for broke with the 4.6GHz profile. The AI Suite software did its thing, and after a quick reboot, the system was running our combined CPU and GPU stress test at 4.6GHz. CPU temperatures spiked as high as 80°C, but the machine was stable, and there was no evidence of throttling after a few minutes under load.

Next, I turned my attention to manual overclocking via the firmware. I started by increasing the CPU multiplier, and 4.5GHz came easily, with no need to modify any other settings. 4.6GHz proved more elusive. The system booted at that speed without issue, but it either ran too hot, causing throttling, or it produced BSOD errors under load, causing a system crash.

I couldn’t find a combination of voltage and power settings that kept the CPU stable at 4.6GHz. A second auto-tuned run at that speed proved more successful at first, but a BSOD error appeared after less than 10 minutes under load.

Haswell overclocking is typically limited by one’s cooling apparatus and the characteristics of individual chips. This particular CPU-and-cooler combo is usually good for 4.5-4.6GHz. The Maximus VI Impact takes this CPU as far as the best Z87 boards we’ve tested. Meanwhile, the Impact’s firmware and software interfaces make the overclocking process easy, regardless of whether you’re a seasoned enthusiast or an uninitiated newbie.

Performance and power consumption
When they’re not cheating with higher Turbo ratios, motherboards these days have little impact on performance. It’s been that way for years. The CPU and GPU matter the most for applications and games, and SSDs can improve overall responsiveness. To be sure, we ran the Maximus VI Impact through a range of application and peripheral tests. The board performed as well as all the other Z87-based products we’ve tested with the same system hardware. There were a few minute performance differences here and there, but nothing worth graphing.

Motherboards play a greater role in dictating system power consumption. We quantified the Impact’s efficiency by measuring power consumption at the wall socket with the test system at idle, playing a 1080p YouTube video, and under a full load combining Cinebench rendering with the Unigine Valley DirectX 11 graphics demo. These tests measure full system power consumption.

As the only other Mini-ITX board in the bunch, the ASRock Z87E-ITX is the most appropriate foil for the Impact. The Asus board has higher power consumption at idle and when playing YouTube video. However, it draws 10W less under full load, suggesting that fancy power riser isn’t just for show.

The Impact’s lower power draw under load is especially appealing for gaming and high-performance rigs. The Z87E-ITX’s advantage at idle is more attractive for basic desktops and home-theater PCs that won’t be pushed to their limits.

Detailed specifications
We’ve covered most aspects of the Maximus VI Impact already. In case we missed anything, here’s a full rundown of the key specifications and firmware options.

Remember, that’s all on a Mini-ITX motherboard. Pretty impressive.