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MSI X99s SLI Plus Atx Lga2011-3 Motherboard

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While every X99 computer motherboard can use all 16 lanes from the -5820K on the uppermost slot, MSI is the only company that chooses to untether eight of them for use by the third slot across its entire X99 motherboard series. Even the cheap ones.

We can also see that the X99S SLI Plus is capable of distributing a higher-end processor’s 40 lanes across all four slots, facilitating four-way SLI. GeForce cards supporting four-way SLI all have double-slot brackets, and the X99S SLI Plus’ third and fourth slots are single-spaced.

Pathway Switches

The rather clever use of pathway switches even allows the X99S SLI Plus to support three-way SLI and an M.2-interface PCIe 3.0 x4 SSD simultaneously, which I probably only think is clever because it’s the first configuration I thought of when Intel revealed that the Core i7-5820K has 28 lanes.

The X99S SLI Plus’ feature set is extensive enough to actually confuse us. To begin, it has all of those PCIe 3.0 switches that its competitors couldn’t afford to add, which enable combinations like three-way SLI and PCIe 3.0 M.2.

The company then adds six more USB 3.0 ports through two add-in controllers, increasing the total port count (including two front-panel headers) to twelve, while competitors limit their USB 3.0 port count to six on their X99 model.

You’ll find a lighted CLR_CMOS button on the I/O panel in addition to the basic stuff. Sliding down the edge a little we also find another unusual feature (by budget-oriented board standards): a row of voltage detection points including both DIMM rails, CPU I/O, CPU core, and PCH voltages.

MSI doesn’t even mention this feature in its X99S SLI Plus user manual. As with the X99S SLI Plus’ ability to run a fourth PCIe x16 graphics card, it’s an “Easter egg”.

Most Important Feature

One capability that would be standard on ATX-based X99 motherboards is the second set of DIMM slots corresponding to each of the platform’s four channels. That’s eight slots. The only competing sub-$200 X99 board has four. Any of us can appreciate the added expense of including the full set of slots.

Other Features

Other internal features include a PCIe connector that extends the bottom two (outward-facing) SATA ports into SATA-Express, a dual-BIOS switch (next to the SATA-E interface), Power/Reset/OC Genie buttons just below the last PCIe slot and a total of five four-pin PWM-style fan headers. The OC-Genie button engages MSI’s automatic overclocking and validation routine without installing the bundled software application that does the same thing.

The X99S SLI Plus includes MSI’s full utility suite, with applications to reboot directly to firmware, update your drivers and firmware from an MSI server, reduce power by disabling fans and ports, and quick-charge your portable devices.


3D Gaming

Game benchmarks are only truly meaningful when comparing different GPUs (Battlefield 4, Far Cry 3), CPUs (Arma 3), or memory (Grid 2). Readers still request these in motherboard reviews on occasion, and the tests add only around 30 minutes to a single-board evaluation.

Non-Gaming Applications

Our encoding, creativity, productivity, and compression benchmarks are extremely useful for comparing processors, memory configurations, and the OpenCL capabilities of graphics cards. None of those results changes in a motherboard comparison.

Then again, our automated process runs these benchmarks while we’re busy doing other things.
Lower might be better in a timed test, but less is more when it comes to motherboard evaluation. That’s because close results prevent lengthy investigations.

Power, Heat And Efficiency

MSI’s X99S SLI Plus runs mid-pack in both power and heat, compared to similarly-priced models. Our overall performance and efficiency charts are slightly different in that they contain the results of all 12 boards we’ve reviewed since the X99 launch.

Because less expensive motherboards have fewer features, we find all three of the boards in the MSI X99S SLI Plus comparison producing higher efficiency numbers compared to the overall average. Getting more specific, the X99S SLI Plus falls between the two most closely-priced models in both power and efficiency.

MSI’s X99S SLI Plus includes a reasonably broad range of voltage and clock settings at relatively small intervals, yet produces a CPU clock that’s on par with the other standard motherboard.

It appears that MSI gets its grand DRAM to overclock by using conservative timings. If you want top memory performance on the X99S SLI Plus, your best bet is to buy fast RAM and set it to XMP defaults.


Budget Friendly Motherboard

Is the X99S SLI Plus the best solution for budget buyers? MSI thinks so and put quite a bit of technology into this product to prove its worth. The manufacturer even added four two-lane PCIe 3.0 switches to enable three-way SLI on Intel’s Core i7-5820K.

But MSI doesn’t stop with three-way SLI support. The company also adds a couple more switches to enable PCIe 3.0 x4 M.2 SSDs, or a graphics card in the fourth slot and PCIe 2.0 x2 M.2, or SATA 6Gb/s x2 M.2. That’s a lot of M.2 options.

And users who don’t like M.2 can still get top SSD performance in an off-motherboard drive via SATA-Express, which is also missing from competitively-priced products. You can’t run SATA M.2 and SATA-Express, or run the M.2 slot in PCIe 2.0 x2 mode with SATA-Express, since those connections are shared, but even high-end boards with both interfaces have that restriction.

Pros and Cons


  • 3-way SLI support on Intel Core i7-5820K
  • SLI functions with a PCIe 3.0 x4 M.2 SSD
  • USB 3.0 ports


  • Only one SLI bridge included
  • Previous-generation audio code

Check it out on Amazon


The X99S SLI Plus a high-end board at an entry-level price. The six added-in USB 3.0 ports is just magnificent. MSI even equips the board with twice as many DIMM slots as its closest competitor. It appears the only high-end features we don’t get are a “Port 80” status code display and a secondary network interface. Those value-adds aren’t missed much.

This is also the only moderately-priced motherboard to support memory at data rates beyond DDR4-3200. We totally recommend the motherboard as the best entry-level buy. To see other products, visit

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