RAM Timings - tRFC

[Nagasaki]

So I watched a video from Buildzoid ages ago about ram timings for Ryzen and I just swaped my 5800X for an X3D IO thought id go and re-watch it and sort my ram timings out.

 

In his video someone had thier tRFC at over 1000 and mine was also 1047 and he was saying that this was bad, a big no no dont do that.

 

So, I managed to get mine down to 650 so far. Sadly I have 2 kits of ram, Both are the same model from Corsair but the actaul chips are not the same. One kit is SK Hynix and the other is Micron so it's making getting beter sub timings tricky as 1 kit is better at some timings and the other kit is better at others, Anway..

 

What I wanted to know is what is bad about having tRFC so high exactly?

 

I have not noticed anything performance wise to be better so far.

[RONOTHAN##]

The real ratio that matters is tRFC to tREFI. That ratio is the percent of time your RAM is unusable for any sort of data operation. If you have a tRFC of 1000 and a tREFI of 10000, 10% of the time your RAM is refreshing (refilling the capacitors) and therefore unusable. If you're down at 500 tRFC or even lower (250 is possible on some DDR4), you're then only spending 5% or 2.5% of your time refreshing respectively and can get a lot more operations done in that amount of time. 

 

On AM4, tREFI is locked and not user adjustable, meaning that the only way to bring that percentage down is to lower tRFC as much as possible. On Intel, it matters less as you can just set the refresh interval to 65000+, so even a tRFC of 1000 would still mean you're refreshing for 1.5% of the time. 

[Mark Kaine]

1 hour ago, Nagasaki said:

What I wanted to know is what is bad about having tRFC so high exactly

generally...nothing... ram speed and timings are mostly overrated... i mean will ~5fps more really give you an edge? (in some cases maybe, but generally no)

 

What's way more important for performance is having dual channel RAM (even at default speeds) as that gives huge benefits over single channel. 

 

 

*hypocrisy because i oc my 3200 ram to 3600 even though it shouldn't actually matter especially for my 5800x3D... but i did test it quite extensively and 3600 felt snappier,  no fps boost or anything,  just more responsive  -- and im still not sure if its just placebo lol*

 

Tldr: none issue,  just make sure your RAM is actually stable and in dual channel mode

[WereCat]

If its Micron E-die then you may be able to get it down to 545-560 at 3800MT/s but it's dependant on your SOC voltage and DRAM Voltage. 

 

At 3800MT/s I can get 545 tRFC that passes RAM Test for over 10k% coverage but has issues during cold boot. 

 

3 minutes ago, Mark Kaine said:

generally...nothing... ram speed and timings are mostly overrated... i mean will ~5fps more really give you an edge? (in some cases maybe, but generally no)

 

What's way more important for performance is having dual channel RAM (even at default speeds) as that gives huge benefits over single channel. 

 

 

*hypocrisy because i oc my 3200 ram to 3600 even though it shouldn't actually matter especially for my 5800x3D... but i did test it quite extensively and 3600 felt snappier,  no fps boost or anything,  just more responsive  -- and im still not sure if its just placebo lol*

 

Tldr: none issue,  just make sure your RAM is actually stable and in dual channel mode

It does matter even for 5800X3D but the benefit is in the exact same scenarios where the extra L3 cache is huge benefit as well, outside of that the gains are negligible. 

[freeagent]

tRFC can have more of an effect than tight primaries. I run mine at 255.

[Nagasaki]

These are my ram timings at the moment, 

 

Dose anyone see anything thats drasticly wrong? As long as its "good enough".

[freeagent]

7 hours ago, Nagasaki said:

These are my ram timings at the moment, 

 

Dose anyone see anything thats drasticly wrong? As long as its "good enough".

If its stable and running fine for you, then its good enough.

 

Here is a shot of mine.