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.
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112 Comments on AMD Ryzen 3000 "Zen 2" a Memory OC Beast, DDR4-5000 Possible

#101
londiste
RedwoodzSupposedly not tied strictly 1:1 now. What I meant is everything on Zen+ is 12nm. With I/O die on package @ 14nm they do not have to be tied @ 1:1 ratio.
Whether chips are made on 7nm, 12nm or 14nm process has absolutely nothing to do with this. This is an architectural or configuration decision.
Posted on Reply
#102
Super XP
bonehead123Nice, IF it works as expected, and if it does, could we therefore look forward to having DDR-7@10k speeds in a few years for example ???



So if this is the case, why not just replace the IF with optical or another more advanced interlink method ??
IF is already well advanced, and most likely better than most interlink methods. IF can Handle any speed you throw at it, but it seems the actual ZEN design can't at the moment.
I am sure AMD is working out a way to allow ZEN to accept faster IF speeds, and hopefully we will see much faster IF interconnect speeds with ZEN3+
londisteWhat Ryzen so far benefits from with fast memory is the increased IF link speed between CCXs which should be slower no matter what memory timings or speed gets to be.
Edit: reading up on IF speeds in current Zen, I assume AMD doubled the width of IF links from CCX to RAM, otherwise the divider would also limit RAM bandwidth.
This is the entire problem and reason for introducing the divider - IF cannot run at that high a clock. There is hope that AMD has improved IF in Zen2 but we will ahve to wait and see what approach they have taken with it.
Once again, IF is not the issue here from how I read into it, the issue is that the Current ZEN CCXs cannot handle faster IF speeds, if it would, AMD would have added a multiplier where it would run IF at 2x or 3x the IMC. IF isn't the problem here people, but again ZEN is a new design, and I am sure AMD is working it out so it can accept faster IF speeds,
Nevertheless, even with the latency hit due to CCX to CCX communication, ZEN runs amazing and is king of Multi-threading. Newer ZEN designs will only add to this achievement.
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).
I am curious to see Benchmarks & Stability Tests done on manipulating this "New 1/2 Divider Mode" if possible to pump up the IF speed and see what happens. :D:nutkick:
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#103
dumo
DDR4 5000 with Samsung B-die is possible
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#104
GoldenX


And here I am happy with this.
Posted on Reply
#105
TheMadDutchDude
Still stuck at 4333 on my setup. I guess this will have to wait a little while longer.
Posted on Reply
#106
dumo


DDR4 5K with Samsung B-die
Posted on Reply
#107
cucker tarlson
can FCLK be overclocked ?
I mean can you push 1:1:1 ratio higher than 3733mhz ?
Posted on Reply
#108
EarthDog
cucker tarlsoncan FCLK be overclocked ?
I mean can you push 1:1:1 ratio higher than 3733mhz ?
Yes. But not much past it AFAIK.
Posted on Reply
#109
TheMadDutchDude
On what board did they hit 5k? I’m still very curious as to why mine hard walls at 4333.
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#110
dumo
TheMadDutchDudeOn what board did they hit 5k? I’m still very curious as to why mine hard walls at 4333.
Impact/formula for Asus, Godlike for MSI and Aqua for Asrock

With B-die @ 4800C14 and fclk 1900, almost match 9900K with identical memory settings
Posted on Reply
#111
dumo
Asus ROG Crosshair VIII Impact

B-die 5K DOCP with 4800C18 @ XMP





Posted on Reply
#112
johnny-r
I played around with DRAM Calculator over the weekend, wow ! I can really set my ram to its limits, way to go AMD ! I knew it is gonna be sweet but did not realize the potential with RAM is so huge !

last week Msi released some new bios updates and I grabbed the latest release for my B450m gaming plus, the latest release addressed memory compatibility issues, I've also noticed my post is much faster than before especially when I reboot, it was not just zen 2 compatibility issues on the older chipset but memory too, all sorted now, way to go Msi !
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