The Take Away
We all know that SMT can have a major impact on heavily threaded applications, and it's a godsend, but on the flip side, when applications aren't that heavily threaded it can be beneficial to turn it off. The benchmarks with heavily threaded applications show its benefits, and other applications such as some games and even Handbrake in certain configurations do better with SMT off. The results from UMA/NUMA do in fact show the benefits of AMD adding in a second option to make the memory more easily accessible to physically local cores, and the impact on memory latency is huge compared to the difference in memory bandwidth.
There are still applications that benefit from UMA, such as HandBrake and other content creation software, and even some games prefer distributed UMA mode over local NUMA mode. AMD's Gaming Profile with their Legacy Mode really does make a big difference as well, and we did see its benefits in games.
Threadripper employs multiple dies to create a single CPU, and in doing so introduces us to something we aren't used to, the die to die interconnect. The die to die interconnect does run over 100GB/s bi-directionally, but it also imposes a latency penalty. Threadripper's size and interconnects create a new dilemma we haven't really had to face in the past. AMD clocks near memory latency at 78ns, while far memory latency is 133ns, and that difference is huge.
However, while we are faced with this new dilemma, it's one that we will become more familiar with as time progresses, and we aren't able to shrink cores anymore. Multiple die CPUs are going to be part of the future of HEDT platforms, and I have to say that AMD has done a great job with tackling the dilemma. AMD didn't think in the box, but rather out of the box, and gave the consumer the tools to tune their CPU to the maximum.
AMD took the lead and created an easy to use software application which can not only control SMT, but also memory access, and offers a special mode for gaming. AMD's Ryzen Master program is more useful than most people thought, and the difference it can make in real-world performance can't be ignored.
The good news here is that AMD has created, unlocked, and shown us the tools to enhance the Threadripper experience. If you are a crazy tweaker, then it's up to you to play around and see what modes and combinations your programs enjoy the most.
PRICING: You can find the product discussed for sale below. The prices listed are valid at the time of writing, but can change at any time. Click the link below to see real-time pricing for the best deal:United States: The AMD Ryzen Threadripper 1900X (8-core/16-thread) Desktop Processor (YD190XA8AEWOF) retails for $171.66 at Amazon.United Kingdom: The A Look at AMD's Threadripper CPU Hardware Modes retails for £XXX at Amazon UK.Canada: The A Look at AMD's Threadripper CPU Hardware Modes retails for $264.29 CAD at Amazon Canada.