Friday, May 10th 2019
AMD Ryzen 3000 "Zen 2" a Memory OC Beast, DDR4-5000 Possible
AMD's 3rd generation Ryzen (3000-series) processors will overcome a vast number of memory limitations faced by older Ryzen chips. With Zen 2, the company decided to separate the memory controller from the CPU cores into a separate chip, called "IO die". Our resident Ryzen memory guru Yuri "1usmus" Bubliy, author of DRAM Calculator for Ryzen, found technical info that confirms just how much progress AMD has been making.
The third generation Ryzen processors will be able to match their Intel counterparts when it comes to memory overclocking. In the Zen 2 BIOS, the memory frequency options go all the way up to "DDR4-5000", which is a huge increase over the first Ryzens. The DRAM clock is still linked to the Infinity Fabric (IF) clock domain, which means at DDR4-5000, Infinity Fabric would tick at 5000 MHz DDR, too. Since that rate is out of reach for IF, AMD has decided to add a new 1/2 divider mode for their on-chip bus. When enabled, it will run Infinity Fabric at half the DRAM actual clock (eg: 1250 MHz for DDR4-5000).
This could turn into an additional selling point for AMD X570 chipset motherboards, as they'll have a memory frequency headroom advantage over boards based on older chipsets as their BIOS will include not just the increased memory clock limit, but also the divider mode. Of course this doesn't mean that you can just magically overclock any memory kit to these 5 GHz speeds - it's probable that only the best of the best modules will be able to get close to these speeds.
1usmus also discovered that the platform adds a SoC OC mode and VDDG voltage control. We've heard from several sources that AMD invested heavily in improving memory compatibility, especially in the wake of Samsung discontinuing its B-die DRAM chips.
The third generation Ryzen processors will be able to match their Intel counterparts when it comes to memory overclocking. In the Zen 2 BIOS, the memory frequency options go all the way up to "DDR4-5000", which is a huge increase over the first Ryzens. The DRAM clock is still linked to the Infinity Fabric (IF) clock domain, which means at DDR4-5000, Infinity Fabric would tick at 5000 MHz DDR, too. Since that rate is out of reach for IF, AMD has decided to add a new 1/2 divider mode for their on-chip bus. When enabled, it will run Infinity Fabric at half the DRAM actual clock (eg: 1250 MHz for DDR4-5000).
1usmus also discovered that the platform adds a SoC OC mode and VDDG voltage control. We've heard from several sources that AMD invested heavily in improving memory compatibility, especially in the wake of Samsung discontinuing its B-die DRAM chips.
112 Comments on AMD Ryzen 3000 "Zen 2" a Memory OC Beast, DDR4-5000 Possible
Assuming without divider memory goes to 3600 (roughly how it is now), going from 3600 to 4000 and enabling the divider to facilitate these speeds would mean IF clock going from 1800 to 1000, right?
IMC is in the CPU, so divider support in BIOS could theoretically be available for older boards as well.
Regardless, they should be a decent upgrade from a 1000 series chip, at least for gaming.
Maybe it is an earnest effort to improve on the uArch. All I can do is wait and watch. (And stay out of any incoming drama)
Zen's memory "issues" come down to AMD having to draw the line somewhere and come up with a finished product. When they did that, a lot of tweaking for the memory controller got thrown under the bus (read: postponed to Zen2). The I/O chip has nothing to do with that. That was moved to a separate chip because AMD concluded the memory controller doesn't scale and so it will continue to be built on 14nm.
There are a lot of improvements in X 570, MSI and ASUS are preparing legendary tops ;)
Edit: btw big thanks for all the time you have dedicated to Ryzen RAM calculator, it didn't seem to work out for me the last time I used it though I notice you have since released a newer version and I may download that again now and try and shoot for 3400+ on my RAM which I've not been able to acheive as of now.
What point is a 16/32 core proc where you are capped at 16GB dual channel if you want to run high speed dimms.