AMD Ryzen memory optimisation - The effect of tRC timings

AMD Ryzen tRC Timings - A Discovery

AMD Ryzen memory optimisation trick

tRC Timings - A Discovery

With AGESA version 1.0.0.6, AMD Ryzen users are able to adjust a lot more memory settings than before, giving us the option to change the tRC timings of our memory. 

 

Ryzen and Stock tRC Timings

When looking at several different DDR4 memory kits at varying speeds, we found one common thing that for Ryzen's stock tRC timing, with the value changing depending on memory speed but offering the same real-time value of around 0.047 microseconds. 

This means that tRC will have much more room for improvement with higher speed memory, where stock tRC timings are highest, with our G.Skill Trident Z memory allowing this timing to drop to 48 at 3200MHz. This is an improvement of 36% for this specific timing.  

The important thing to note here is that your memory kit's rated (XMP) tRC timings are not being used here, but they are defined by your motherboard. These tRC timings are used by every Ryzen motherboard that we have tested so far, leaving room for optimisation. 

 

Memory Clock SpeedActual Clock SpeedStock tRC TimingTime passed per memory clock (Nano Seconds)Time passed for tRC (Micro Seconds)
2133MHz1066MHz500.93810.0469050
2400MHz1200MHz570.83330.0474981
2666MHz1333MHz630.75020.0472626
2800MHz1400MHz660.71430.0471438
2933MHz1466MHz690.68210.0470649
3200MHz1600MHz750.62500.0468750

 

Finding out what your tRC Timing XMP value

First users should find out what their memory tRC timings should be, which can be commonly found using CPU-Z. tRC is typically the values of tRP (RAS# Precharge) and tRAS added together, which is this case is 48 (14+34) for our G.Skill Trident Z kit. This is found for this memory on the XMP-3200 section of the memory's timings table. 

This means that we are planning to reduce the tRC time from 75 to 48 in the BIOS, which is a 36% reduction, which should increase your system memory performance in certain scenarios. 

It is important to note that tRC should not be lower than tRP + tRAS for stability reasons, though you can use speeds that are higher than this if required.  

Alternatively, you can check your memory's XMP table on other application, or inside your BIOS on select motherboards. 

 

AMD Ryzen memory optimisation trick

 

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Most Recent Comments

18-07-2017, 13:59:45

Chrazey
I like it how the test rig specs in the box say "1080 Founders Edition", although the picture of the PC under it shows and ASUS Strix card Quote

18-07-2017, 14:02:05

WYP
Quote:
Originally Posted by Chrazey View Post
I like it how the test rig specs in the box say "1080 Founders Edition", although the picture of the PC under it shows and ASUS Strix card
That is the thing with test beds, hardware changes all the time. I can't take pics with every hardware configuration.Quote

18-07-2017, 14:08:58

Chrazey
Quote:
Originally Posted by WYP View Post
That is the thing with test beds, hardware changes all the time. I can't take pics with every hardware configuration.
No no, I understand dude. I was just pointing it out, not to put it in your face or anything though.Quote

18-07-2017, 16:49:54

harrison
For whatever it's worth, my memory/motherboard does not seem to exhibit this issue. My XMP 2.0 values populated and booted without any fussing, and the tCR value is accurate.

MB: ASRock AB350M Pro4, BIOS v2.5 (AGESA 1.0.0.6)
Ram: Corsair LPX 2x8GB 3200MHz C16 (CMK16GX4M2C3200C16S)
Timings: 16-18-18-36-54-1 (tCAS-tRC-tRP-tRAS-tCS-tCR)
https://valid.x86.fr/te3x7z

A new update was just released today for AGESA 1.0.0.6a, so I'll need to see how that impacts things, but in this one case at least, things appear to not wonky.Quote

18-07-2017, 17:12:14

WYP
Quote:
Originally Posted by harrison View Post
For whatever it's worth, my memory/motherboard does not seem to exhibit this issue. My XMP 2.0 values populated and booted without any fussing, and the tCR value is accurate.

MB: ASRock AB350M Pro4, BIOS v2.5 (AGESA 1.0.0.6)
Ram: Corsair LPX 2x8GB 3200MHz C16 (CMK16GX4M2C3200C16S)
Timings: 16-18-18-36-54-1 (tCAS-tRC-tRP-tRAS-tCS-tCR)
https://valid.x86.fr/te3x7z

A new update was just released today for AGESA 1.0.0.6a, so I'll need to see how that impacts things, but in this one case at least, things appear to not wonky.
Well that is certainly a positive thing to hear, one of the main points for this is to raise awareness and get a potential fix in future BIOS' if possible. I do remember the Taichi having the issue at launch, so this is likely a recent development.

Hopefully other manufacturers will soon follow suit. It is memory performance that is simply sitting on the table.Quote
Reply
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