The AMD X399 Chipset and Quad Channel memory

The Ryzen Processor Family

Before we begin, let's first talk a little about the processors and  X399 motherboard chipset that accompany them. On the market, you will spot Ryzen series 3, 5, 7 and now Threadripper processors. It’s plain and simple and, as always, that works out the best to understand product positioning compared to the Intel line-up. We’ll go into more detail on the next few pages, of course. 

Ryzen Threadripper will have to battle Intel's new Core i9 (Skylake-X) models that run from 10 to 18 cores with prices running up-towards 2000 USD. AMD launched Ryzen with three primary 8-core models initially, followed by six and four-core models. The Ryzen Threadripper series processors are twelve or sixteen-core processors at incredibly competitive pricing.

• The flagship processor is the Ryzen Threadripper 1950X, a 16-core product that will get a 3.4 GHz base frequency with the ability to precision boost to 4.0 GHz (!). These processors are SMT, thus ‘hyper-threaded’ towards 32 threads. This processor will retail for 999 USD.
• The Ryzen Threadripper 1920X is the 12-core product, the base clock is a notch higher at 3.5 GHz with a precision boost to 4.0 GHz, thus SKU will get 24 threads. This processor will retail for 799 USD. 
• Ryzen Threadripper 1900X is being introduced as well. This is an 8 cores 16 threads, 3.8 base frequency and 4.0 GHz boost. $549 obviously since it is on the X399 platform it is benefiting from quad channel memory as well as the 64-pcie lanes. 
   

You already have seen a number of X399 motherboard announcements, and it is no secret that processors will initially be released in the HEDT (High-End Desktop) segment. Available starting August 10th 2017 and AMD will initially release two models: a 16-core, 32-thread model, and a 12-core, 24-threaded model, followed shortly by that 8-core SKU offering you quad-channel memory and 64 lanes of PCIe gen 3.0. That memory will run the same clock as the infinity fabric. So with the entire platform, you are not making any compromises. 

The X399 Chipset

While some of the chipset functionality is harbored inside the processor, a new generation and architecture processor will always require a new motherboard chipset. Let me first reiterate and make clear that ALL Ryzen processors are unlocked, that entails all Ryzen 3, 5, 7 and thus now the new Threadripper processors. Threadripper processors, however, will require a new socket due to the many pins needed. The platform will be using Socket design SP3r2, a 4094-pin socket that was originally developed for the AMD Naples (EPYC) series server processors, but again, AMD did a 180 and is introducing it also as high-end desktop platform series processors and chipsets. The socket will also be called TR4. 

The massive processing power that Threadripper offers is balanced by more memory bandwidth via quad DDR4 channels, and it’s backed by up to a whopping uncompromising 64 PCIe 3.0 lanes for things like multiple graphics cards, many ultra-fast NVMe SSDs and fast USB and Ethernet. Threadripper ready motherboards will come with 8x DDR4 DIMM modules that can hold a total of 128 GB of DDR4 memory and you will often see 4x PCIe x16 slots and support for up to three NVMe M.2 drives on these motherboards as, well the motherboard manufacturers have enough PCIe 3.0 lanes to work with. PCI-Express Gen 3.0 is fully supported on all 64 PCIe Lanes, that means you also get full support for the NVMe protocol, USB 3.1 Gen 2 (10 Gbps) and M.2 and SATA Express support. Since Ryzen architecture processor has all the IO paths and a controller built in for USB 3.1 (Gen 2) as well there will be PCI lanes dedicated to your NVMe needs.
 

 
As such the X399 chipset will support multi-GPU rendering (Crossfire and SLI) with up-to four mechanical x16 PCI Express slots (Gen 3.0) and connected from there onwards endless possibilities in your configuration, say 16x/16x/8x/8x Gen 3.0.
 

 
The Ryzen threadripper processor has an I/O of 64 PCIe 3.0 lanes. The interlink between the Threadripper processor and X399 chipset is a 4x PCIE Gen 3 link - and then your X399 chipset will also offer additional 20 (!) PCIe Gen 2 lanes and 12 (!) SATA3 ports. Again, four lanes function as an interconnect to the chipset. In the above screenshot, you can check how that works out compared to Ryzen / X370. 

Quad channel DDR4 Memory

AMD brought DDR4 support to Ryzen 3 5 and 7, that remained to be dual-channel. With Threadripper that quad-channel support is being introduced. The motherboards will be paired with eight DIMM slots, configurable as single, dual and quad channel setup. AMD will support the standard Jedec SPD timings and frequencies at 2133/2400 and 2667 MHz, but you can expect to see motherboards to support 3200 MHz (and higher up-to 3600 MHz) as well, much like Ryzen with AGESA 1006 and newer offers. Two channels per two 4 DIMMS per 2 dies and will offer UMA (distributed) versus NUMA (local) modes (for low gaming latency). The new memory subsystem will run 3200 MHz in quad-channel with no problems (with compatible memory). 

AMD's Memory Configuration options - Uma (Distributed) or Numa (Local)?

With everything that is going on at Threadripper you already know that the physical size and layout of the processor is big. That also means some DIMM DDR4 channels are closer, while others are farther away from the memory controllers. You could describe that as near memory and perhaps far memory based on the distance of the two processor chips its cores inside the package. Near memory has a latency of in the sat 77ns ranges while far memory can pass 120ns. AMD’s solution is to use Ryzen select (in BIOS or Ryzen Master) two memory modes that.
 

 
UMA is the Distributed Mode memory control - it is the platform default and allows software to use all the DRAM evenly Local Mode NUMA uses local memory near the die or chip to gain lower 66.2ns latency. Obviously, the number of modules of memory installed is trivial here, but we assume most end-users will use 4 DIMMs in quad-channel.
 

 
This option will become available in Ryzen Master, but you can use the BIOS option to switch between the two memory modes. Generally, older/less threaded games might run a slightly faster in the Local mode while latest games/heavily threaded (e.g. Ashes) will run better with the default Distributed mode. Very simply put, distributed mode offers better bandwidth, local mode offers lower latency. Our advice, play around with it a bit and run both modes to get the complete picture and select your preference. We can see Gamers end up in local mode, and say video editors at the default distributed mode.