ASUS Prime X399-A

By contrast to the comparison between the two ASRock motherboards, ASUS has positioned their first two products further apart from each other. The Prime X399-A is aimed more at an entry into X399, although the ‘entry’ moniker might be misleading: these X399 motherboards are still being stacked to the hilt in functionality even for the ‘cheaper’ models.

The ASUS Prime X399-A follows previous Prime-A products in a white/grey styling, using a brushed metal and angled design across the heatsinks and PCB to show that this motherboard means business (or something like that). The key features of the Prime X399-A are going to be the extended power delivery heatsink arrangement, U.2 and M.2 storage support, ASUS’ upgrade to the Realtek audio and RGB support. 

The baseline specifications for the majority of Threadripper boards are here: a full complement of 8 DIMMs for memory, a good set of PCIe slots for multiple-add in cards, SATA storage, Ethernet and USB 3.1 (10 Gbps) support. ASUS, by comparison to the ROG Zenith, has stripped this model down: there’s only one Ethernet port, no WiFi, only two M.2 slots, fewer USB ports (but still over a dozen), and fewer PCIe slots with reinforcement. Threadripper is a high-end product, so doing a complete strip down to the bare essentials negates the high-end aspect of the platform. Perhaps a surprise over the ROG is that the Prime-A has a two-digit LED debug, while the ROG does not.

Going through the board in detail, starting at the top, is the VRM arrangement. This is an eight-phase design, with a dual connected heatsink reaching around the memory slots to the rear panel, which has a small 40mm fan. On the other side of the socket, ASUS has placed both EPS connectors (one 8-pin, one 4-pin) on the top right of the board with the 24-pin ATX connector directly below. While this area is where ASUS normally places some of its more esoteric features, such as PCIe slot disabling switches, there is no need to here. Perhaps a little strange to most will be the placement of the M.2 slot underneath the 24-pin, which requires the M.2 be placed ‘standing-up’ and out of the board. ASUS provides an M.2 bracket to assist in rigidity here.

Below the M.2 is the onboard USB 3.1 (10 Gbps) header from the chipset, which is slowly becoming adopted as the onboard standard, with a small number of chassis manufacturers adopting it for adding front-panel ports. This is followed by one of the two USB 3.0 headers, a U.2 port, and six SATA ports.

The chipset heatsink, as shown by the RGB on the picture, houses a few LEDs to adjust the aesthetic through the onboard AURA SYNC software. The heatsink also houses an M.2 slot, like the ROG, and helps provide additional cooling for it if needed.

To the left of the chipset are the PCIe slots. In order to save some cost and provide a little bit of product differentiation, ASUS has decided to only equip three of the full-length slots with a reinforcement guard, although all four full-length slots are connected to the CPU. The full length slots are provided as x16/x8/x16/x8, and when users equip multiple graphics cards, the slots with the reinforcement guard are the best ones to use. The one without the guard is not worse in any way, however in a two or three card system, using x16/x16 or x16/x16/x8 is usually preferred to x16/x8 or x16/x8/x8 due to the slot spacing arrangement. There is an additional PCIe 2.0 x4 from the chipset present as well.

Below the PCIe slots are the onboard headers, including USB 3.0 headers, fan headers, RGB LED headers and a two-digit debug. This is also paired with a power button to test the motherboard when a hand is in the case but the case is not hooked up. To the right of this is the onboard audio, to which ASUS uses their customized version of the Realtek ALC1220. This is combined with upgraded filter caps, PCB separation, an EMI shield and a DTS software stack.

The rear panel, due to the positioning of the board, might look a little bare compared to the ROG. There is the BIOS reset button, a total of eight USB 3.0 ports, the gigabit Ethernet port provided via the Intel I211-AT controller, a USB 3.1 Type-A port and Type-C port from an ASMedia controller, and the audio jacks with SPDIF output. 

ASUS Prime X399-A
Warranty Period  3 Years
Product Page Link
Price $349.99
Size E-ATX
CPU Interface TR4
Chipset AMD X399
Memory Slots (DDR4) Eight DDR4
Supporting 128GB
Quad Channel
Up to 3600 MHz (OC)
Network Connectivity 1 x Intel I211-AT GbE
Wireless Network N/A
Onboard Audio SupremeFX S1220A
PCIe Slots for Graphics (from CPU) 4 x PCIe 3.0 x16
Supports SLI/CF
PCIe Slots for Other (from Chipset) 1 x PCIe 2.0 x4 (max)
1 x PCIe 2.0 x1
Onboard SATA 6x Supporting RAID 0/1/10
Onboard SATA Express None
Onboard M.2 2 x PCIe 3.0 x4 - NVMe or SATA
Onboard U.2 1 x 
USB 3.1 1 x Type-A Port
1 x Type-C Port
USB 3.0 8 x Rear Panel Ports
2 x Headers
USB 2.0 2 x Headers
Power Connectors 1 x 24-pin EATX
1 x 8-pin ATX 12V
1 x 4-pin ATX 12V
Fan Headers 1 x M.2
1 x CPU
1 x CPU OPT
3 x Chassis 
1 x AIO_PUMP
1 x 5-pin EXT_FAN
IO Panel 1 x Intel NIC
1 x USB 3.1 Type-A 
1 x USB 3.1 Type-C

8 x USB 3.0 Ports
1 x Optical S/PDIF out
5 x Audio jack 
1 x USB BIOS Flashback Button
ASUS ROG Zenith Extreme ASUS ROG Strix X399-E Gaming
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  • ddriver - Monday, September 18, 2017 - link

    You should look up into it. A gas turbine is not a jet engine. It is actually more efficient, and it doesn't utilize jet propulsion. Gas turbines power certain tanks, ships and helicopters. They are also used in power plants.
  • thomasg - Sunday, September 17, 2017 - link

    Honestly, could you just stop bringing your stupid gas turbine rant, since you don't really seem to grasp what efficiency is, and not even what power a typical engine has.

    Gas turbines are very efficient in use at or around their designed typical load. They are not efficient under medium and low load scenarios, where they will drop below modern gasoline combustion engines.

    Those come with 200 kW - in high-powered sports cars, or top-of-the-line luxury limousines.
    A "entry level car" will be at max. 75 kW peak power; and guess what: most of the time they are used far below the maximum output.

    Modern gasoline car engines typically reach 45% efficiency, which they achieve in their typical load scenarios, at less than 50% of their design load.

    Modern gas turbines can reach up to 60% efficiency, which is great - but this is usage at their design load. At half load, the efficiency will drop below 30%. The majority of miles driven with cars are at below half load.

    What we expect from car engines is efficiency at their usage, while having enough reserves for quick acceleration. Gas turbines cannot do this efficiently, and gas turbines are notoriously laggy in variable load.

    However, they can be used effectively in fully-hybrid cars, where peak-load is achieved by battery-backed electric motors.
    But since these engines are so expensive to produce, it is simply more cost-effective to use fully-electric cars for this.
  • ddriver - Monday, September 18, 2017 - link

    Of course that a gas turbine consumer vehicle will also utilize a battery buffer. You basically charge it while stationary, drive on battery until power runs out, which is when the turbine is activated to supply power and charge. An all-electric drive will significantly simplify the design, the transmission, and will ensure maximum torque on any level of power.

    You are way off, only F1 engines approach 50% of efficiency, but they only last like a few races, which is the cost of that efficiency. Totally impractical for consumer vehicles. The typical operational efficiency of consumer vehicles is as low as 20%. And they are also intrinsically limited in terms of torque delivery, which happens in a specific and rather narrow RPM range.

    So, transitioning to gas turbine engines will not have a 100% but a 200% increase in efficiency. I guess little minds simply cannot appreciate then significance of that. Not to mention it will defacto force wide hybrid vehicle adoption, and a very overhead compared to internal combustion engines, as a gas turbine with the same power delivery will weight 1/4 of that, and will deliver 3 times as much energy from the same amount of fuel.

    Gas turbine engines are also actually easier to make and maintain, they have far less moving parts. You seem to be confusing a regular gas turbine engine with the ultra-efficient one, which requires expenssive and time staking 5 axis machining of the components. Those exceed 70% efficiency, but if you aim for 60%, the manufacturing is much cheaper, easier and faster. Overall much more cost efficient.

    Which is exactly why they are not being adopted. It will result in massive loss of revenue - cheaper engines, that need less of the expensive maintenance, less parts, and burn much less fuel. The priority of the industry is profit, and gas turbine vehicles will result in a massive dip in that aspect. Internal combustion engines are pathetic in terms of efficiency, but are very profit-effective.
  • ddriver - Monday, September 18, 2017 - link

    "and a very LOW overhead compared to internal combustion engines"
  • vgray35@hotmail.com - Sunday, September 17, 2017 - link

    Get a glue ddriver. This is not about power saved whose numbers are minuscule compared to the power o/p of an automobile engine - IT IS ALL ABOUT TEMPERATURE OF THE INTEGRATED CHIPS WHICH ARE LIMITED TO NOT MUCH MORE THAN 100 deg C, and the difficulty of providing sufficient air flow or liquid cooling necessary to remove that heat. Failure to remove the heat dramatically reduces life of the chips by as much as 60% - 70% life reduction. The problem is greatly curtailed by not using circuity designs that would generate ever larger amounts of waste heat. Please stick to subject matter of this posting, which is about reducing CPU and GPU and VRM operating temperatures, without using huge heat sinks and liquid cooling radiators. How does one reduce these temperatures? The first step is to eliminate >85% of the heat in the ATX PSU, motherboard VRMs, and GPU VRMs, to reduce total heat load on the cooling system. And that technology is already available as mentioned above. Please cease with the 100 kW rhetoric which is meaningless in context of this temperature problem (yes little k for kilo not capitol K). Let's talk about the excess temperature issue. Get it!

    Thread Ripper is a HEDT platform and thus deserves a HEDT VRM solution, and not the same old worn out technologies that use air-gapped ferrite cored inductors, when resonance scaling permits increased resonant capacitance in exchange for much smaller resonant inductance using cheaper air-cored inductors. And to boot, a dramatic reduction is both size and cost. AMD should lead this charge and bring forth an appropriate reference VRM, using PWM-resonant switching and resonance scaling of the Cr/Lr resonant components. ARE YOU LISTENING AMD - LETS RETIRE THE BUCK CONVERTER ACROSS THE BOARD.
  • ddriver - Monday, September 18, 2017 - link

    Getting glue. Now what?

    Here is a clue - remove the stock heatsink, install better cooling. Takes like 5 minutes. Heat problem solved. Crude, but it delivers result.

    The industry standards are so low, there is barely a product, regardless of its price range, that someone with basic engineering cannot tangibly improve in a few easy steps.

    An example, I recently got a yoga 720 2in1. Opened it up, removed the cooling, put good TIM, reinstalled cooling, now I have a 5 minute 5$ improvement that gave me a 10% boost in performance, temperature and battery life. They are just lazy, and don't go even for the most obvious, easiest to implement improvements.

    They DONT WANT IT TO RUN COOL. They deliberately engineer it to run at its limit, so close that often they actually mess it up. So that this device can fail, so you can get a new one. It is a time bomb, planned obsolescence, and you can bet your ass they would have done the same regardless of the power delivery circuit involved. It may actually be a far more delicate and harder to address time bomb than hot running VRMs. Which you can easily cool down by ordering a custom heatpipe solution, which will set you back like 50$. That's a rather quick and affordable way to solve your problem, compared to complaining about it in this cesspool of mediocrity ;)
  • vgray35@hotmail.com - Monday, September 18, 2017 - link

    Sorry ddriver, but I disagree with all your perspectives on this matter. You are clearly not capable of addressing the technical issues of Power Supply design for efficiency, and cannot get to grips with electronic circuity (or do not want to) and how different designs compare. You appear only interested in hijacking the original subject matter for your own purposes. You never contributed a single element addressing the original purpose of this thread, and so you have lost your credibility as a serious participant in my book, and hence you and I done.
  • glennst43 - Friday, September 15, 2017 - link

    Based on my experience with the Asus Zenith Extreme, you can expect a bumpy ride which should not be surprising with a new product. My last 3 systems were Intel X58, X79, and X99 boards purchased shortly after thier releases, and this platform (x399) has had the most issues. I expect that in a few months after some BIOS and driver updates, the experiecne will get much better. I suspect that the validation process is not as thorough as the Intel boards.
    Here are a few issues that I have experienced as an early adopter:
    System would not boot with 2 video cards (resolved with BIOS update)
    The 10G Network card would randomly disconnect (resolved? with driver update)
    System sometimes will not come back from sleep and requires a hard reset (no resolution yet)
    USB devices disconnecting/reconnecting randomly (no resolution yet)
  • johnnycanadian - Friday, September 15, 2017 - link

    I'm crossing my fingers I made the correct choice with MSI's x399 offering. I too have been burned by the ASUS early-adopter-penalty and although Gigabyte has been good to me in the past, the MSI offered everything I needed and then some (although I'm firmly in the "get rid of the tacky LED" camp). Everything is getting stuffed into a Cooler Master HAF XB II EVO (with no glass but with the mesh top panel). Even if it's not perfect it can't be worse than running Windows on Boot Camp with a "trash can" (aptly named) Mac "Pro".
  • arter97 - Friday, September 15, 2017 - link

    ASUS PRIME X399-A : "In the ROG board this lead to a 40mm fan, which is not present here on the Prime."

    This is wrong. I own one and the fan is present under the shroud.
    You can even see it from the side shot of the motherboard.

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