Given that this is an HEDT motherboard that is fueled by Ryzen Threadripper power, there are a total of eight DDR4 DIMM slots supporting a total of 128GB. As for memory speeds, the board can handle 3400MHz+ frequencies. Onboard you'll find a total of three PCIe 3.0 x16 slots that can wrangle up to three AMD Radeon graphics cards in a CrossFire configuration or two NVIDIA GeForce graphics cards in SLI.
On the storage front, there are eight SATA III connectors with the X399 chipset supporting RAID 0, RAID 1 and RAID 10. For those that require a faster storage subsystem, there are three M.2 PCIe 3.0 x4 slots.
When it comes to wired connectivity, ASRock has your bases covered with an Intel-based Gigabit Ethernet controller and a Realtek 2.5Gb Ethernet controller. If you're looking for a standard onboard wireless controller, you won't find one here, unfortunately. However, there is an M.2 Key E connector for those that wish to add an 802.11ac adapter.
For those that like to load up on peripherals, you'll find two USB 3.1 Gen 2 connectors (one Type-A, one Type-C) and a total of 12 USB 3.1 Gen 1 ports (eight on the rear I/O plate and four headers at the front of the motherboard). As for audio, the X399 Phantom Gaming 6 uses a Realtek ALC1220 audio codec and an NE5532 amplifier along with Nichicon Fine Gold audio capacitors.
And if that wasn't enough, being that this is a gaming motherboard, the PCH heatsink features RGB LEDs that are compatible with ASRock's own Polychrome RGB lighting.
The ASRock X399 Phantom Gaming 6 supports both first- and second-generation AMD Ryzen Threadripper processors, meaning that you can load one up with a beastly 32-core/64-thread Ryzen Threadripper 2990WX. Pricing and availability have not yet been announced for the motherboard.