This week MSI has announced the availability of a new motherboard built for Threadripper: the X399 SLI Plus. MSI says the SLI Plus is an optimized workstation motherboard built for designers. Like the X399 Gaming Pro Carbon, it uses heavy plated heatsinks and 'Military Class VI' components. Although MSI is aiming at the professional market, they have still added plenty of features for gamers and enthusiasts as well, given the overlap in requirements. 

The MSI X399 SLI Plus

As with other X399 boards, the MSI X399 SLI Plus uses eight total memory slots, although these are not reinforced. This configuration allows for up to 128GB of RAM in a quad channel setup. MSI uses their DDR4 Boost technology on the SLI Plus and lists memory speed support up to DDR4-3600+. 

Power delivery is handled by a fully digital 13 phase VRM which looks quite similar to the Gaming Pro Carbon AC. Per the Military Class VI specs, it uses Titanium chokes and 'dark' capacitors. We cannot confirm by the pictures, however, it is likely using the same DrMOS ICs found on the Pro Carbon. Power is fed to the VRMs by two 12V CPU leads (one is optional) located in the upper left-hand corner of the board. The SLI Plus has a full two character debug LED as well as a simplified four LED debug system with LED’s for Boot, VGA, DRAM, and CPU.

The SLI Plus has a total of six PCIe slots: two PCIe 2.0 x1 slots and four full-length PCIe 3.0 slots. The two main GPU slots, capable of running x16/x16 if they are the only ones populated, are reinforced with MSI’s Steel Armor to support heavy video cards and prevent potential damage to the slot. The motherboard supports 4-Way NVIDIA SLI and 4-Way AMD Crossfire technologies.

For storage, the SLI Plus has a total of eight SATA ports fed from the chipset, and has the same physical location and orientation of the Pro Carbon; six horizontal and two vertical. There are a total of three PCIe 3.0 x4 M.2 slots which get their lanes from the CPU. Two of the M.2 slots support up to 80mm drives, while the middle slot can handle up to 110mm modules. Only the top M.2 slot has a heatsink for cooling down the installed M.2 module. U.2 support does not make it to the SLI Plus.

The audio side of the house is managed by a Realtek ACL1220 codec working in conjunction with MSI’s Audio Boost 4 suite. While the Nahimic software package normally found on the gaming products does not make its way here, the SLI Plus uses separate audio layers for left and right channels, de-pop protection, Chemi-Con audio capacitors, EMI shielding and board separation, and a dedicated headphone amplifier which auto-detects impedance (use up to 600Ω).

As far as the overall aesthetic, MSI uses a black PCB and color scheme and lets the integrated RGB LEDs fit whatever theme a builder has in mind. LEDs make it on the back panel IO shroud, chipset heatsink, and a strip found on the back of the board under the SATA ports. Additional RGB LED strips can be added via the two onboard RGB headers. One is for a rainbow strip, while the other for general RGB; both are controlled by MSI’s Mystic Light software. 

Pricing was not listed, but we do expect the SLI Plus to come in under the Gaming Pro Carbon. Previous HEDT SLI Plus motherboards have often been the cheapest available, and it would be abnormal if this board was different. We should see these available for purchase soon. 

Warranty Period 3 Years
Product Page Link
Price N/A
Size ATX
CPU Interface TR4
Chipset AMD X399
Memory Slots (DDR4) Eight DDR4
Supporting 128GB
Quad Channel
Up to 3600 MHz (OC)
Supports ECC UDIMM (in non-ECC mode)
Network Connectivity 1 x Intel Gigabit LAN controller
Onboard Audio Realtek ALC1220
PCIe Slots for Graphics (from CPU) 4 x PCIe 3.0 x16
PCIe Slots for Other (from Chipset) 2 x PCIe 2.0 x1 
Onboard SATA 8 x Supporting RAID 0/1/10
Onboard SATA Express None
Onboard M.2 3 x PCIe 3.0 x4 - NVMe or SATA
Onboard U.2 None
USB 3.1 1 x Type-C (ASMedia)
1 x Type-A (ASMedia)
1 x Internal Header
USB 3.0 4 x USB 3.0
USB 2.0 2 x Back Panel
2 x Headers
Power Connectors 1 x 24-pin ATX
2 x 8-pin CPU
Fan Headers 1 x CPU (4-pin)
1 x Water Pump (4-pin)
4 x System Fan (4-pin)
IO Panel 1 x Clear CMOS button
1 x BIOS FLASHBACK+ button
1 x PS/2 keyboard/mouse combo port
2 x USB 2.0 Type-A ports
8 x USB 3.0 Type-A ports
1 x LAN (RJ-45)
1 x USB 3.1 Type-A port
1 x USB 3.1 Type-C port
5 x Audio Jacks
1 x Optical S/PDIF OUT connector

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Source: MSI

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  • shabby - Tuesday, October 10, 2017 - link

    Marketing 101, what gamer would want a board "specifically" made for content creators? Can't believe these guys get paid, what's next a board made for office productivity?
  • MrSpadge - Tuesday, October 10, 2017 - link

    That would be the same without the LEDs ;)
  • mapesdhs - Wednesday, October 11, 2017 - link

    LEDs = the SJWs of the tech world. :)
  • nagi603 - Tuesday, October 10, 2017 - link

    That top PCIe slot looks waaaaay too close to the memory. As in, clearance could be a big issue if one would want to populate all the PCI and Memory slots. And with a TR, you would. (Why else buy one?)
  • DanNeely - Tuesday, October 10, 2017 - link

    It's the same spacing you see with any dimm and a full length PCIe card in the first slot. Assuming that like most modern boards that do so they're using single ended latching dimms sockets there should be no problem at all. If they're using old fashioned double ended latching dimm sockets you'll probably need to pull the GPU to change ram out; but again that's nothing new.
  • Topweasel - Tuesday, October 10, 2017 - link

    Tons of mobo's put a 1x PCIe port there specifically for this reason.
  • DanNeely - Tuesday, October 10, 2017 - link

    Which is fine if you only need to support at most 3 GPUs. 4 GPUs requires one in the top slot, and while many more recent boards have moved the 1st slot down to make more room it isn't and never has been necessary to do so.
  • mapesdhs - Wednesday, October 11, 2017 - link

    Yup, should be fine with any AIO or better, which is much more likely to be the go-to type of coole for a TR build.

    I like the look of this build, so tired of all the flashy bells & whistles of recent designs. Anything LED is just wasted cost I don't care about.
  • shabby - Tuesday, October 10, 2017 - link

    It's not as bad as some asus boards that have the cpu socket a few millimeters from the pcie slot.
  • ddriver - Tuesday, October 10, 2017 - link

    It's ok, as long as you don't install memory after populating the top pcie slot. Not a problem during PC assembly, as you install memory before gpu anyway. You might have to remove the gpu if you are upgrading or replacing ram, but not that much of a big deal.

    Of course, you can also opt to not use the top slot, there appear to be at least 2 other that are x16 electrically, so no big whoop unless you need all the slots.

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