# Ryzen DRAM Calculator and tRFC



## mgilbert (Sep 17, 2019)

On the main page, the Ryzen DRAM calculator recommends a tRFC value of 288 for my RAM.  However, my UEFI also asks for values for tRFC2 and tRFC4.  Those values are not given on the main page.  I found an online article that says tRFC2 should be (tRFC  / 1.346), and tRFC4 should be (tRFC2 / 1.625).  That yields values of 214 and 132 for tRFC2 and tRFC4.

However...  On the "Additional Calculator" page or the DRAM calculator, there is a calculator for the tRFC, tRFC2, and tRFC4 values.  When I plug in the values required, obtained from the main page, that calculator gives values of 390, 290, 178 for tRFC, tRFC2, and tRFC4.

Can someone explain the three tRFC functions - and which set of values I should use???


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## jesdals (Sep 17, 2019)

Just leave them to auto, if the the rest fint and you cant thighten cl more then try to lower trfc and then the rest. I found that trfc could go down by 5 points at the end of tweaking


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## Zach_01 (Sep 17, 2019)

On the first (main) page of DRAMcalc, after you click the "R - XMP" button what is the *tRFC ns* you see on first column? What profile version are you using (V1, V2) and what frequency (MT/s)?


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## mgilbert (Sep 17, 2019)

Zach_01 said:


> On the first (main) page of DRAMcalc, after you click the "R - XMP" button what is the *tRFC ns* you see on first column? What profile version are you using (V1, V2) and what frequency (MT/s)?



260 nS, V1, 3,000 MT/s...


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## TheLostSwede (Sep 17, 2019)

Are you sure you're using the latest version?
They're in the DRAM calculator, but it also says to there's no need to change them on Ryzen processors.


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## mgilbert (Sep 17, 2019)

TheLostSwede said:


> Are you sure you're using the latest version?
> They're in the DRAM calculator, but it also says to there's no need to change them on Ryzen processors.



Yes - version 1.6.2, downloaded yesterday, from this website.  The tRFC value is listed on the main page, but not the tRFC2 or tRFC4 values.  There is a calculator for determining tRFC and those two extra values on the "Additional Calculators" page, but it returns a different tRFC value than the one on the main page.  My BIOS asks for all three, and there is no "Auto" for any of the three.  I'm sure I can get away with using the more conservative values provided by the calculator on the "Additional Calculators" page.  I can't imagine it would make much difference.


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## Zach_01 (Sep 17, 2019)

Try both... first use the one on main page and calculate the tRFC2/4 by the... (tRFC / 1.346), and tRFC4 should be (tRFC2 / 1.625) rule.
You can try the alternative also from the main page. And you can try later the values on the "Additional Calculators" page.

Mine too gives different tRFCs between the pages (ver1.6.2).
Maybe the one on Additional Calculators is more of a standar/typical for the given MTs/s and tRFC ns, and the one from main page is in correlation with the other settings (safe/fast settings)


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## NoJuan999 (Sep 17, 2019)

What CPU and Motherboard/BIOS do you have ?
If you have a 3000 series CPU, you might need to wait for a BIOS update that improves Memory OC performance/Compatibility.

I used the DRAM Calculator when I had a Ryzen 5 2600 (OC'd to 4GHz) on an Asus ROG Strix B450-F and it worked great.
BUT, I tried it for my current 3700x (with the same RAM) and I can't OC any better than the DOCP (XMP) profile besides lowering some of the Primary timings.
I'm 99.9% sure it is a BIOS issue. so hopefully at some point I will be able to get my RAM back to 3400 MHz with tighter timings like I did with my 2600.


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## mgilbert (Sep 17, 2019)

Zach_01 said:


> Try both... first use the one on main page and calculate the tRFC2/4 by the... (tRFC / 1.346), and tRFC4 should be (tRFC2 / 1.625) rule.
> You can try the alternative also from the main page. And you can try later the values on the "Additional Calculators" page.
> 
> Mine too gives different tRFCs between the pages (ver1.6.2).
> Maybe the one on Additional Calculators is more of a standar/typical for the given MTs/s and tRFC ns, and the one from main page is in correlation with the other settings (safe/fast settings)



That sounds like a good plan.  Thanks...



NoJuan999 said:


> What CPU and Motherboard/BIOS do you have ?
> If you have a 3000 series CPU, you might need to wait for a BIOS update that improve Memory OC performance/Compatibility.
> 
> I used the DRAM Calculator when I had a Ryzen 5 2600 (OC'd to 4GHz) on an Asus ROG Strix B450-F and it worked great.
> ...



Well, I'm still on an ASRock x370 board with a Ryzen 1700 processor.  I'm going to upgrade, but I just can't afford it right now.


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