3600mhz CL18 vs 3600Mhz CL14 - how much difference really on Ryzen?

alec · 20 Oct 2020 at 09:25

Guest2 said:
If Zen 3 is 1900mhz tops, then why do we even need 3600mhz ram? Sorry for my ignorance. I’ve been using ddr3 ram for many years

DDR marketing does that to you.
DDR4-3600 is not MHz, its MT for megatransfers. DDR is double data rate, so for every tick there are two transfers. Actual frequency of memory is half - so 1800 MHz.

Zen 2 and 3 perfrom best when memory is synchronous with their internal bus clock, Infinity Fabric (FCLK). Thats what was referred to 1900MHz tops. Meaning there was no point in using memory faster than DDR4-3800. Overclocking memory now mostly consists of tightening timings at that speed.

Zen 3 is rumored to up the FCLK limit to 2000MHz. Meaning higher tier kits up to DDR4-4000 come into discussion

Guest2 · 20 Oct 2020 at 09:59

alec said:
DDR marketing does that to you.
DDR4-3600 is not MHz, its MT for megatransfers. DDR is double data rate, so for every tick there are two transfers. Actual frequency of memory is half - so 1800 MHz.

Zen 2 and 3 perfrom best when memory is synchronous with their internal bus clock, Infinity Fabric (FCLK). Thats what was referred to 1900MHz tops. Meaning there was no point in using memory faster than DDR4-3800. Overclocking memory now mostly consists of tightening timings at that speed.

Zen 3 is rumored to up the FCLK limit to 2000MHz. Meaning higher tier kits up to DDR4-4000 come into discussion

Great explanation, thanks.

Checking AMD site on the 5900X page it says

System Memory
System Memory Specification
Up to 3200MHz

Does this therefore mean that upto DDR4-6400 (MR) is supported. I’ve never even seen DDR-6400 RAM

clv101 · 20 Oct 2020 at 10:08

No, the 3200 = 1600MHz. However AMD are suggesting that the 5000 series might overclock to 2000MHz = DDR-4000.

Guest2 · 20 Oct 2020 at 10:24

clv101 said:
No, the 3200 = 1600MHz. However AMD are suggesting that the 5000 series might overclock to 2000MHz = DDR-4000.

Oh yeh, by bad. half not double

Do we (anyone) know when/if AMD will make an announcement about DDR-4000 support? Possibly on day of release of 5000 series or the day before :rolleyes:

clv101 · 20 Oct 2020 at 10:47

It'll be discussed in the reviews as AMD specifically mention it in documentation still under NDA.

BigBANGtheory · 21 Oct 2020 at 10:59

Presumably the CL14 kit will also run better at higher frequencies too I.e. looser timings than 3600 but better than other kits even those advertised at higher frequency specs?

Guest2 · 21 Oct 2020 at 15:41

Would it be better to get 2 sets of these (CAS14) so buy 2 2 x 8GB sets

Team Group RIPPED Edition 16GB (2x8GB) DDR4 PC4-28800C14 3600MHz Dual Channel Kit - Black/
CAS 14-15-15-35 Timings
https://www.overclockers.co.uk/team...3600mhz-dual-channel-kit-black-my-001-8p.html

Or go with these (CAS16) 2 x 16GB set when they are in stock

Team Group Edition 32GB (2x16GB) DDR4 PC4-28800C16 3600MHz Dual Channel Kit
CAS 16-16-16-38 Timings
https://www.overclockers.co.uk/team...00c16-3600mhz-dual-channel-kit-my-002-8p.html

What in the world is 'RIPPED' ??

alec · 21 Oct 2020 at 15:53

Guest2 said:
What in the world is 'RIPPED' ??

RIPPED translates to COSTS MORE.
Would go with 2x16, better chance to work compared to 4x8 generally

Guest2 · 21 Oct 2020 at 15:58

alec said:
RIPPED translates to COSTS MORE.
Would go with 2x16, better chance to work compared to 4x8 generally

Are right. A nice marketing word.
In that case it should have been marketed as 'Artisan Ripped' for another £50 more

Mr Oblong · 21 Oct 2020 at 21:33

alec said:
RIPPED translates to COSTS MORE.
Would go with 2x16, better chance to work compared to 4x8 generally

RIPPED RAM has more PROTEIN

BigBANGtheory · 22 Oct 2020 at 15:58

Guest2 said:
Would it be better to get 2 sets of these (CAS14) so buy 2 2 x 8GB sets

Team Group RIPPED Edition 16GB (2x8GB) DDR4 PC4-28800C14 3600MHz Dual Channel Kit - Black/
CAS 14-15-15-35 Timings
https://www.overclockers.co.uk/team...3600mhz-dual-channel-kit-black-my-001-8p.html

Or go with these (CAS16) 2 x 16GB set when they are in stock

Team Group Edition 32GB (2x16GB) DDR4 PC4-28800C16 3600MHz Dual Channel Kit
CAS 16-16-16-38 Timings
https://www.overclockers.co.uk/team...00c16-3600mhz-dual-channel-kit-my-002-8p.html

What in the world is 'RIPPED' ??

faster RAM modules vs. use of 4 slots yeah its a tricky one

I believe what causes the limitation is the effect of crosstalk and interreference on the memory bus, therefore if your motherboard is well made with lots of PCB layers faster RAM in theory would be better except in extreme cases such as LN2 OC where the frequencies are abnormally high... assuming its all single rank memory modules which it should be for 8GB

Awahwah · 22 Oct 2020 at 16:24

Guest2 said:
Are right. A nice marketing word.
In that case it should have been marketed as 'Artisan Ripped' for another £50 more

4x8 was difficult for me to get working other than 3200 CL14 (XMP). 2x8 OC's to 3600 CL14 with easy - this is on a x570 Taichi. I'd say stick with 2 sticks if possible.

Guest2 · 22 Oct 2020 at 20:03

I was looking at 2x16GB but noticed this 64GB kit of 3600Mhz CAS18 RAM

https://www.overclockers.co.uk/cors...3600mhz-dual-channel-kit-black-my-4cf-cs.html

Would this be better than a 2x16GB kit thats CAS16 like the 8 Pack RAM?

Or maybe this instead - https://www.overclockers.co.uk/cors...00c18-3600mhz-dual-channel-kit-my-4cd-cs.html

alec · 23 Oct 2020 at 10:05

Not better but bigger. And worse latency.
If you have any application that could use that much memory, it is a pure win for price/gb. Otherwise a waste.
2x32GB sticks also overclock worse than 2x16GB, mostly because built on slower dies. Most top out at 3733.
But it could be better compared to 4x16GB, because they strain motherboard and memory controller less

BigBANGtheory · 23 Oct 2020 at 13:56

alec said:
Not better but bigger. And worse latency.
If you have any application that could use that much memory, it is a pure win for price/gb. Otherwise a waste.
2x32GB sticks also overclock worse than 2x16GB, mostly because built on slower dies. Most top out at 3733.
But it could be better compared to 4x16GB, because they strain motherboard and memory controller less

So I thought (and I could be mistaken here) that the memory controller strain comes from the number of memory ranks in use rather than the slots i.e. 2 slots using double rank memory = 4 slots using single rank, but 2 slots using single rank was best

Therefore 16GB memory modules with single rank would potentially be beneficial but you're already sacrificing some timings on those modules.... So would 4x8GB with room for looser timings end up in the same place, better or worse? I don't know the answer to that but what I would say is Dual Channel memory should run at its advertised speeds and nowhere does it say 2 slots only....

alec · 23 Oct 2020 at 17:03

BigBANGtheory said:
Therefore 16GB memory modules with single rank would potentially be beneficial

Note most 16 GB modules are dual rank still.
One exception is Crucial Ballistix Max line, with notably high speed 2x16GB kits that are single rank.
Bottom line, it is easier to find good overclocking 8GB sticks than 16GB. And 32GB sticks won't clock much at all.