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AMD Ryzen memory optimisation — The effect of tRC timings | AMD Ryzen tRC Timings — A Discovery | CPU & Mainboard

AMD Ryzen tRC Timings — A Discovery

Published: 14th July 2017 | Source: OC3D Internal testing | Price: | Author: Mark Campbell

tRC Timings — A Discovery

With AGESA version, 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 Speed Actual Clock Speed Stock tRC Timing Time passed per memory clock (Nano Seconds) Time passed for tRC (Micro Seconds)
2133MHz 1066MHz 50 0.9381 0.0469050
2400MHz 1200MHz 57 0.8333 0. 0474981
2666MHz 1333MHz 63 0.7502 0.0472626
2800MHz 1400MHz 66 0.7143 0.0471438
2933MHz 1466MHz 69 0.6821 0.0470649
3200MHz 1600MHz 75 0.6250 0.0468750


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. 



1 — Introduction2 — AMD Ryzen tRC Timings — A Discovery3 — Changing tRC timings and stability testing4 — Performance testing and methodology5 — AIDA 64 — Memory Performance and Latency6 — Cinebench R157 — Geekbench8 — x265 Benchmark9 — 3DMARK Performance 10 — VRMARK11 — Hitman (2016)12 — Gears of War 413 — Total War: Warhammer14 — Conclusion«Prev 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Next»

Most Recent Comments

18-07-2017, 18:02:05


18-07-2017, 21:12:14



Perfect RAM Timing Rule (Posting Resuts Of Using The Rule Is Appreciated)

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I was uploaded it years ago 12-18-13

Orignally From another overclocking website
Conversation can be OFFENSIVE

Posting negative results are also appreciated, as it will tell us that the rule is Wrong

I recomend using this rule when you are overclocking so hard that all of your timings needs to be changed to increace overcloking freedom

Rule applies to any DDR RAM (DDR1,2,3,4)

Spoiler is to keep record of the old version posted. Ignore it cause it is wrong.

You can also try with stock ram frequency and keep the CL same but use the rule

My oppinion
Stock clocks and stock CL but using the rule will allow the RAM to operate with less error and run more smooth
Giving increace in performance (ignoring that it can be slower in bench marks)


Keep in mind lower numbers means higher ram performance

CL depends on your ram performance

You can single clock down CL for quick RAM tune up
leaving everything else stock

1T will give higher performance
2T will give higher RAM frequency
3T will give higher RAM frequency

Find the balance between 1T or 2T memory clock capability giving you best performance




4.TFAW=TRRD+TWTR+TCWL+TRTP+TWR (TWR which stays the same with the twr rule TRTP+TRCD)

5.Ratio Rule for TCL-TRCD-TRP is 9-10-8 (Cl Lowest-TRCD Highest-TRP Middle)

6.Ratio Rule for TFAW (Back Timings) TRRD+TWTR+TCWL+TRTP (TRRD lowest, TWTR mid low, TCWL mid high TRTP highest)
Which TRRD is simular to CL which decides the RAM operating speed

7.Decreacing TRC and TRAS by -1 to -20 can increase ram write performance
Depending on how much it can take

Normally manufacture uses -3 TRC and TRAS

8. Higher TRCD and higher TRP should give higher frequency also trc and tras needs to be changed

(TFAW timing rule hasn’t been tested in overclocking yet, this is only an test theory which I will use in overclocking my RAM on the fxa990 gd80 msi
I also need to check by looking at the ram timing setting avalible in my FXA990 GD80 MSI before I can be fully sure that it is right for the back timings
Also I need to upload a ram timing table screen shot of my MSI BIOS later on)

Recomended Rule to use




Depending on RAM module it will only operate on certain Row Refresh Cycle frequencys, there are 2 or 4 ramtimings for this,80ns, 160NS or 300NS or 350NS (DDR3 RAM)
Example 1600 RAM runs on 160NS, 2400RAM will not run below 300NS even at 1600 speeds
You will want to try out 300NS or higher when your overclocking FSB allot. As you may be able to break your FSB barrarier by setting this higher.

For 1T2T timings, you will need to set it at 2T for high FSBS, unless it operates with the FSB clocked.
Again setting 2T or 3T or higher can break your max FSB barrier

Using CL ratio rule and back timing ratio rule
Higher TRCD and higher TRP should give higher frequency also trc and tras needs to be changed

For back timing Twr and TRRD is bascally simular thing to CL and you need to read before you write
Meaning that trrd must run faster than twr

RAM speed can be modeled by CL divided by MHZ, lower numbers result in faster RAM
8/2133=0.00375, which means CL8 2133 is faster than Cl10 2400

For fastest ram speeds, aim for lowest CL and lowest TWTR and TRRD
Lower CL means faster RAM, lower numbers means faster timmings.


TRP= your RAM speed Example 2400RAM will need a setting of 12 or higher
2133 will Need a setting of 11
Thus 13X2=26X100=2600, therefore to run 2600 RAM this timing must be 2600 Or higher
(note that TRCD shouldn’t be smaller than TRP, it should be equal or higher)
You should increace TRCD when small amounts of stabibility is needed, because the speeds are to fast for the ram to handle. You can also manually add 1 clock to TRAS and TRFW, therefore stabibility will increace, as there is a 1 clock or more delay for stuff to finish before going onto next step

You need to have a certian number of TRAS and TRFC to run certain frequencies, you may want to leave it as cl+2X tTRCD then try CL+TRCD+TRRD(EG the 2400 tidrent X needed 30-42 minimum to run stalbe)

TRRD Must Be smaller than TWTR, Typically TWTR should be 1 click higher than TRRD
TRRD= 20
(These are bascally read write time CL Depping on how much your RAM can take, the lower you can set it the faster it is)

TWR =Manually specify for performance, Typically 2clocks higher than TRRD should be the fastest setting. Depends on how fast your ram can run.
Typically the minimum TRTP setting on a DDR3 RAM is 5 clocks, unless you BIOS mod you cannot go lower. As the name implies Time Read To Precharge and Time Wrte to Load, it is the diffrence in your TRRD and TWTR timming compared with TWR For DDR3 a typical TWR setting is TRRD+TWTR=TWR

TWL= TWR minus Twtr

Typically, If your CL can be set at CL7, your TRRD should be able to run at 5 or lower.
It is best to have TWTR one click lower than CL ( TWTR at 6).
TRRD+TWTR can be even lower when you want a higher OC. But it shouldn’t get you far, as your CL timing will be bottle necking your very fast TRRD and TWTR, in terms of stabibility and performance, CL at 20 means your TRRD should be at 18 and TWTR should be at 19

Command Rate depends on your RAM module, Lower numbers are faster
(setting this at 2T or higher can yeild higher max FSB OC)

TRFC0,1,2,3,4 Depends on RAM module, lower numbers are faster
(setting this at 350NS or higher can yeild higher max FSB OC)

Ram can operate with approximatly a +- 3 timings from optimal timing,
But TRRD must be smaller than TWTR, no tollerance for that. You can try your self and you will find out. make TWTR lower than TRRD and you will not boot up

Refer to image, It is also a example of a perferct 2133 RAM oc setting Vadilation of the system with this timing (Its a Gskill 2400CL10 2X8GB water cooled)