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Gigabyte x99 Phoenix SLI motherboard- 2

Time for the motherboard itself. It comes in a foam package as seen before:


Taking the motherboard out, and flipping the package gives a good base to start examining the board. There are plastic covers on the I/O cover and audio heatsink, and as always it is a pleasure to remove them.. slowly:


Once removed, we get a better look at the x99-Phoenix SLI in its full glory:




As is a norm these days, a matte black PCB is used with all other components soldered in place. The motherboard itself has multiple layers and traces go through, under and over the layers to help connect different components. The solder quality is good and there are very few outlying solder balls or spikes anywhere allowing one to hold the board without necessarily hurting themselves. There is no motherboard backplate- partial or whole- here unlike what a few others have adopted, but as we will see soon the reinforcement that comes from this has been provided separately elsewhere.

Let’s go over the board now, beginning with the I/O section:


No real surprise here given we saw the I/O shield before, but going from left to right we have:

  • A PS/2 keyboard/mouse port
  • Two USB 3.0 ports (Type A female, Blue) backwards compatible with USB 2.0/1.1
  • Two male SMA connectors to connect the WiFi antenna to
  • A USB 3.1 port (Type C female) backwards compatible with USB 3.0/2.0
  • A USB 3.1 port (Type A female, Red) backwards compatible with USB 3.0/2.0/1.1
  • Two RJ-45 Intel Gigabit Ethernet LAN ports (10/100/1000 Mbit)
  • Four USB 3.0 ports (Type A female, 3 Blue + 1 special white) backwards compatible with USB 2.0/1.1. The white colored USB port is compatible with Gigabyte Q-Flash/Q-Flash Plus technology allowing BIOS flashing via a USB drive
  • Audio section with support for 2/4/5.1/7.1 channel system using a Realtek ALC1150 codec with speaker/headset and microphone support along with an optical S/PDIF out connector

While it may look sparsely populated, there is a good feature set here and reliance on all Intel parts as much as possible. There is ESD protection provided for the USB and LAN ports which is nice to see. The USB 3.1 ports are handled by an Intel Alpine Ridge USB 3.1 controller, as opposed to an ASMedia controller which some competitors have adopted, and Gigabyte claims this gives a boost in the allowed max bandwidth to the ports. Either way, it is supported by PCI-E Gen 2.0 x4 for up to 20 Gbps bandwidth (not Gen 3.0 x4, as supported by the Intel z170 chipset) from the x99 chipset rather than the CPU, and this is shared between the two USB 3.1 ports. The rest of the I/O is handled by an iTE I/O controller. There is a plastic I/O cover which is for aesthetics alone and is not a heatsink. On the plus side, it is a separate piece and not connected to the VRM heatsinks thus allowing custom watercooling options for the VRM while yet retaining this cover. Oh, and there are RGB LEDs in here as well. More on that later.

On to the rest of the motherboard now. Let’s go in a clockwise manner beginning from the I/O area itself.


A single 8-pin EPS connector helps power the CPU. I would have really preferred to see dual 8-pin EPS connectors but this is a gaming motherboard and Gigabyte intends heavy overclocking be done on their SOC series of motherboards. That being said, I had no issues getting my I7 5960x to 4.5+ GHz on this where it is consuming well over 300 W itself so most will have no issues with a single connector. You may want to consider the provided 1-3 8 pin connector adapter cable as per Gigabyte’s recommendation though. Alongside is a system fan header, and this is a 4-pin fan header. However, it is a voltage control only fan header with a Ground/Speed control/Sense/VCC pinout. So please be aware of this and do not connect PWM devices here expecting PWM control.





8 DDR4 DIMM slots in total here with 4 on each side, for two separate quad channels that are color coded in black and orange colors to aid in installation. These DIMM slots have an open latch on the top of the motherboard alone, which helps in 2 things- installing and removing memory sticks with the first PCI-E slot occupied, and increasing compatibility for PCI-E devices with backplates that may otherwise hit an open latch. All 8 slots are reinforced with a stainless steel shielding which Gigabyte claims helps prevent PCB distortion. This I have a hard time believing to be functionally needed, as even their demonstration picture in the product page overview uses what seems to be a directed mass in the center of the slot to show said distortion. But they also claim that this shielding helps prevent ESD related component failure and, assuming this is true, makes it worth it in my books. Either way, it is there and you are paying for it. In between the slots are more RGB LEDs under a transparent housing. As far as DDR4 RAM compatibility goes, it is limited by the x99 chipset and the IMC on the specific CPU being used for all practical purposes so the claimed support for XMP 3400 MHz and more is to be taken as a reference more than an assurance of course. Do check the online manual (latest version) for a full list of compatible DDR4 sets.





The Intel x99 CPU socket is as provided from Foxconn to most board partners, but there is some Gigabyte special sauce added. There is a 15 micron thick gold plating on the socket pins, for one. Secondly, despite this still technically being called an LGA 2011-3 socket, there are more than 2011 pins in the socket. This was first seen in some of Asus’ x99 motherboards in 2014 (they called it an OC socket) and it helped with cache/uncore overclocking as well as stabilizing higher DDR4 overclocking compared to a standard Intel LGA 2011-3 socket. Other motherboard makers were working on their own version of this as well, and Gigabyte introduced it with their SOC series of x99 motherboards. This x99-Phoenix SLI gets it as well, and I can confirm it works just as well as the one of my Asus x99 Rampage V Extreme. In fact, here is the socket on the Asus board for comparison:


The capacitors in the middle aside, it looks very similar if not identical. I have not counted the pins on both sockets, but feel free to do so at your interest/peril.


The CPU_Fan header is located just under socket as viewed from the front, which is an awkward position and means that cables will be noticeable. It is a 4-pin PWM header with a Ground/+12 V/Sense/Speed control layout so we are at 1 voltage control, 1 PWM control fan header so far.


To the right of the CPU socket and VRMs, as seen from the front, is the CPU_OPT header. This is one of two hybrid fan headers in that it is a 4-pin header capable of voltage and PWM control (chosen within the BIOS/utilities) with a Ground/Speed Control/Sense/Speed Control layout. Gigabyte calls it a fan/pump header, and it is definitely very handy.



On to the right edge of the motherboard now where we have the 24-pin ATX connector, and also the first internal USB 3.0 header which is capable of providing two USB 3.0/2.0 ports typically on the case. Alongside, and slightly offset, is the Thunderbolt add-in card connector, in case you purchase a Gigabyte Thunderbolt add-in card separately. No power/reset physical buttons here which would have been great for testing purposes but then again this is in their gaming/UD class as I remind myself. That being said, I would encourage Gigabyte (and everyone) to include these and debug LEDs on any high end ATX class motherboard irrespective of the motherboard intended target customer base.


There are a LOT of different storage options here. From left to right, we have four SATA3 ports backwards compatible with SATA2 and SATA1, a SATA Express connector, 6 more SATA3 ports (4 if SATA Express is used, but let’s face it- it is practically dead on arrival as a storage form factor), and a U.2 port (previously called SFF-8639) to finish up this area. The SATA ports support hot-plugging, and the x99 chipset also helps support RAID 0/1/5/10. The U.2 port has support for NVME devices with PCI-E Gen 3.0 x4 support for up to 32 Gbps bandwidth- provided you have a CPU with 40 lanes of PCI-E Gen 3.0 support. Owners of an i7 5820k or 6800k will not be able to use the U.2 port at all. I am ok with this since the add-in PCI-E or M.2 form factors have been more popular and if anything had to go I would rather it be this.


On the bottom right of the motherboard, as seen from the front, is the front panel header for the case complete with power and HDD activity LED headers, power and reset switch headers and a speaker header if your case has a built-in speaker. If you do, then good luck- this is the only real indicator of any issues during start up. There is no debug LED indicator on this motherboard which is a big deal in my books. I would have rather had it instead of some RGB lighting, but for me personally I can make do after having used the x99 platform for so long. Alongside is the second hybrid 4-pin header which can do both PWM and voltage control, and also the second internal USB 3.0 header. So the motherboard can support up to 4 USB 3.0 ports on the case (or elsewhere using adapter cables).



If your case happens to have USB 2.0 ports, then you can use the provided two internal USB 2.0 headers for a total of 4 USB 2.0 ports. Alternatively, adapters and even USB 2.0 brackets/add-in cards will help provide more USB ports internally or externally. These will also be handy if using devices that need internal USB 2.0 headers including Corsair Link, NZXT CAM, Aquacomputer Aquasuite enabled devices. Also here is a TPM (Trusted Platform Module) header which does seem out of place on a gaming motherboard- especially with few TPM modules available as it is. Gigabyte does offer a TPM 2.0 compatible module for separate purchase for those interested. Oh, and the final fan header is here which is another voltage control only header. There are a total of 5 4-pin headers then, 1 PWM, 2 voltage control and 2 hybrid PWM/voltage control headers. I would have definitely liked to see more- especially the hybrid headers- and also more information about the headers themselves. As such, I can only assume they support the usual 1 A power rating each with some leeway for start-up boost. Indeed, they were each capable of powering a 10 W pump so they should be able to handle most fans/low power pumps.




A full size MOLEX connector, rotated 90° to aid in cable management in standard ATX layout cases, is provided to help power the PCI-E slots when 2 or more devices are connected that draw power from the PCI-E slots. Can I just say here how much I would rather see a SATA power or PCI-E power connector here instead? Full size MOLEX needs to not be used as early as possible- it is flimsy, hard to sleeve, and has no practical benefits over SATA/PCI-E. Next to it are the lighting headers- an LED header to be used with the provided RGB LED extension cable, which helps control RGB LED strips conforming to the 5050 RGB (12V/G/R/B) standard and can power a 2 meter long LED strip up to 2 A (24 W) which will suffice for most cases. There is also a demo lighting header but it requires a special 2 pin adapter cable which can then go to a standard male USB Type A port and can be powered by even a power bank. The front audio header and a S/PDIF out header are right by the dedicated audio section on the PCB, and I recommend using the motherboard I/O for audio as it is. There is a heatsink on the audio section, which is also an aesthetic cover and extends to the I/O cover to cover the entire left edge of the motherboard as seen from the front.



There are two M.2 expansion slots on the motherboard, but one (between full length PCI-E slots 1 and 2) comes pre-occupied by an Intel 8260NGW wireless communications module which is wired to the SMA connectors on the I/O. This has support for WiFi 802.11 a/b/g/n/ac on the 2.4 and 5 GHz bands supporting up to 867 Mbps data transfer speeds meaning your router and the path between it and the motherboard antenna will be the bottleneck anyway. It also provides a Bluetooth connection with support for Bluetooth 4.2 and backwards compatibility for Bluetooth 4.1/4.0/3.0/2.1. Given it is a short length M.2 port/device, there is ample space here for the CMOS battery and this makes removing it or changing it out very easy, if required.





The second M.2 expansion slot is between full length PCI-E slots 2 and 3 (PCIEx16_2 and PCIEx8_1) and can accommodate any M.2 device of M key and 2242/2260/2280/22110 type with full PCI-E Gen 3.0 x4 support for up to 32 Gbps bandwidth. I do not have an M.2 device here other than the previously seen Intel wireless module so I was not able to test the port. Installation does seems to conform to the standard, using a two piece screw and nut for the various possible lengths.






There are a total of 5 PCI-E expansion slots on the x99-Phoenix SLI motherboard. From top to bottom, we have PCIEx16_1, PCIEx1, PCIEx16_2, PCIEx8_1 and PCIEx8_2. The naming is fairly straightforward and tells us there are 4 PCI-E Gen 3.0 x16 full length slots here, with 2 providing the full 16 lanes and the other 8 capable of 8 lanes each. Again, this is contingent on the CPU used and also the number of PCI-E devices use/lanes occupied. With an i7 5820k or 6800k, the PCIEx1_2 slot operates in x8 mode and the PCIEx8_2 becomes unavailable, for example. There is a 3-slot spacing between PCIEx16_1 and PCIEx16_2, allowing for even 3-slot air cooled GPUs to be used in the first slot without many issues. This is also the slot recommended for single GPU use, although PCIEx16_2 will also work. There is support for up to 3-way SLI and Crossfire configurations here, although 3-way SLI is becoming a question mark off late anyway.

All the full length PCI-E slots are reinforced similar to the DIMM slots, with a stainless steel shielding to help support heavy GPUs and prevent PCI-E slot distortion. There are extra anchor points to the motherboard PCB to help distribute load better along the length of the slot, and this also aids in preventing the slot being sheared off the PCB due to extraneous circumstances. There are also two locks in each slot which are soldered to the back of the motherboard PCB to further keep the PCI-E device in place and prevent it from coming loose by accident if the lever is slightly out of position. Also note that there is ~4 mm of usable space behind the first PCI-E x16 slot for backplates before they hit the DRAM slots and the I/O cover. So users with thick backplates on GPUs in particular need to be aware of this and be ready to mod the backplates if there is conflict. Oh yeah, more RGB LEDs here as well.

Here is a cheat sheet layout guide for reference, as provided by the manual:



Gigabyte has had a history of unannounced revisions to PCBs, with component changes that sometimes even affect compatibility with aftermarket products and cooling solutions. This particular board is from revision 1.0 and as always, check the bottom left corner, as seen from the front, to make sure you know what revision your own motherboard is from.

With the CPU and memory installed, it does begin to look very nice if I say so myself:


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