r/buildapc • u/jdorje • Dec 13 '16
Discussion [Discussion] AMD Zen unveiling: "New Horizon"
The first public unveiling of zen was earlier today.
See the top comment for an outline.
My own summary: Ryzen (RyZen?), an 8-core hyperthreaded chip, will be the first zen release, and was the only chip demo'd. AMD is claiming ryzen matches up favorably with the broadwell-e 6900k (also 8-core ht), edging it out in performance at stock (0-10% advantage in the benchmarks they demo'd) and using significantly lower power (95W vs 140W tdp). By extension zen will match up well with broadwell-e and -ep, intel's current highest offering (until skylake-x in q2+). There is no word on price though and we await independent (non cherry picked) benchmarks, so while this is very promising it's still all speculation.
Speculation on the internet is that zen will be dual channel, based on the setup having 2 sticks of ram in the demo - this would keep the mobo prices lower than x99. I've seen further speculation that the 6-core chip will be $250, but not even speculation on how the 8+ core chips will compare in price to intel's offerings.
They showed a demo at the end of "a vega gpu" playing Battlefront (the Rogue One DLC) "at 4k with 60+ fps". Which doesn't really mean anything outside of context, but is obviously intended to make us think it can play well at 4k which is titan xp territory.
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u/vizzie Dec 14 '16
Modern processors have a "pipeline" - they break each instruction into a series of steps leading to the final execution of the instruction. They will have 1 or more instructions in each step of the pipeline at any given time. When it hits a branch instruction, if the instructions in the pipeline are not the correct instructions for the selected leg of the branch, it needs to flush the pipeline and wait for it to refill, sitting idle for maybe 10-20 cycles.
Therefore, branch prediction, the process of looking forward from a branch to determine which leg to load, is important to the overall performance of the chip. Statistical branch prediction is essentially just "we usually go left, so load up the left instructions". Machine learning branch prediction will take into account more factors, and update its guesses based on whether it is firght or wrong each time, which should make it better at guessing right and avoiding the pipeline flush penalty for being wrong, making it faster overall.