Ryzen 5900x memory, 4000Mhz CL18 or 3600Mhz CL16?

1 : Anonymous2021/07/10 08:17 ID: ohetcy

I am building a gaming pc with 5900x cpu.
Which one of these memories is better, 4000Mhz CL18 or 3600Mhz CL16?
I know that this cpu is dual-channel, but overall, for this cpu, is 4 sticks have better performance than 2?

2 : Anonymous2021/07/10 08:21 ID: h4ol5q6

3600 CL16. your probably going to have trouble getting the infinity fabric up to 2000mhz. Not impossible, but it will take a lot of time and effort.

ID: h4qd45x

Not impossible, but it will take a lot of time and effort.

2000 MHz FCLK actually stable is a matter of luck, not effort.

3 : Anonymous2021/07/10 09:15 ID: h4oodub

4000 ain't worth it unless you benchmark it with lots of different software and make sure its completely stable. some people have been able to boot with 4000 but get worse performance. success at booting 4000 1:1 fabric also varies depending on both CPU and motherboard, so you might not be able to boot it at all.

4000 kit might be able to get tighter timings if you downclock to 3600 or 3800, though.

4 : Anonymous2021/07/10 09:12 ID: h4oo7cm

3600cl16 will be cheaper. They will perform about the same. 4 sticks will preform slightly better. Depends on how many ranks the modules have. 4 total ranks I think is optimal. It's hard to find information on how many ranks each stick might be. Some are single rank, and some are dual rank. If you get 4 sticks you're guaranteed to get quad rank. 4 ranks total. 2 sticks might be 2 ranks total, or could be quad rank as well.

It'll be close to impossible to get 4 sticks to 4000mhz, unless you really know what you're doing.

ID: h4oqah6

My 5600x could boot and be stable 2x8gb cl16 4000mhz 1:1, 4x8gb no boot at all.

What setting should I look at to try it to boot?

ID: h4ou3qa

It could be your mb, most probably it is daisy chained and not t-topology. I've had similar issues. Daisy chained works best with 2 sticks, while t-topology is quad. I can hit 4000 IF with 2gb but only tested stable at 3866, while I can only boot at 3666 with 4 sticks.

ID: h4qheiy

Motherboard might be daisy chain topology as

said, but it's also greater stress on the CPU's integrated memory controller (IMC) so 4 sticks very often can't run as high frequency and low latency as 2 sticks, regardless of topology.

ID: h4ov96a

4 sticks isnt actually better performance. Unless you have a 4 channel cpu. If you have a dual channel cpu then 2 sticks is better. It will have more bandwith per stick of ram and due to that be faster. This is also the reason why top tier asus mobos have only 2 ram slots

ID: h4psvfv

2 sticks will overclock more easily manually. That's true. But at the same frequency quad rank is faster than dual rank. When I say ranks, I mean ranks. Not channels. A lot of people don't know what ranks are.

ID: h4pqd47

Not sure why I see so many people perpetuating myths around this.

It depends on whether your memory is single or dual rank.

4 x single rank in a 2 channel memory config is the same as 2 x dual rank sticks, one in each channel I.e slots a2 and b2 It's no harder than that.

It's harder to know what you have but generally all 16gb and higher sticks are dual rank. Many 8gb sticks are single rank but not all. Check the manufacturers website or a retailer that is smart enough to include it in the specs.

So I you want to run 16gb using 2 x 8gb sticks then you need dual rank. If you run 32gb in 4x8gb setup, then you want single rank. I you use dual rank you will effectively get quad channel and that crushes the memory controller.

ID: h4qhi4x

Zen3 has tangible benefits.

5 : Anonymous2021/07/10 22:35 ID: h4qy9dc

i recently ordered a 5800x but someone told me ( an idiot i guess ) to get ddr4 4400, is it possible to run it at 3800 with better timings? or should i send the kit back and get a 3600/3800 ?

6 : Anonymous2021/07/10 20:02 ID: h4qh52q

3600 CL16 is cheaper and will perform roughly the same. It also has better stability and compatibility because 2000 MHz FCLK is difficult to get running stable and a lot of boards just won't do it.

Higher FCLK often mandates higher cLDO_VDDP, but for Ryzen 3000 and 5000 CPUs, it should never exceed 1.1v according to AMD, so if 2000 MHz FCLK won't POST for you below 1.1v, you're not getting it to work safely. Higher VDDG CCD voltage can help with FCLK stability as well, while lower SOC and VDDG IOD voltage can improve stability. Just keep in mind that VDDG voltages can't be more than 50mv lower than your SOC voltage, so if your SOC voltage is 1.05v like mine is, your IOD and CCD voltages can't exceed 1v.

Though with luck you can also get 3600 CL16 to work on 3200 CL16 kits, which is exactly what I did with my Corsair Dominator Platinums (CMT32GX4M4C3200C16). I have looser CL16 timings but it's still a fair bit better than XMP. Barely have to adjust voltages from what XMP normally pushes for and the DRAM voltage is the same, 1.35v. (Hynix CJR)

7 : Anonymous2021/07/10 19:47 ID: h4qfkcy

My 5950x will boot and pass memory tests @ c16 w 2x16 b-die. No matter how long I run them (karhu, hci, occt, p95 L FFT, Aida 64) no ram or whea errors pop up and my latency is around 51ns... the usb on the other hand... well... I have to run IF 3600 CL14 instead. The difference between 3600 cl16 and cl14 is negligible but my ram requires 1.45v to do cl14 and the temps shoot up (still testing stable mind you), tested latency is within 1.5ns and my 1%, 0.1%lows, benchmarks are negligibly affected so why drive it harder?

I'd say listen to the general advice I've read in response to your post so far as dailying is concerned but if tuning out dram and IF sounds fun go ham... just have realistic expectations which others here have dropped some insight towards

8 : Anonymous2021/07/10 17:23 ID: h4pz0yh

I would take the 3600 because there is no guarantee that your CPU will be able to run a 2000 MHz FClock stably. Having the option to use the ‘XMP’ profile is valuable for testing even if you plan on doing custom timings.

9 : Anonymous2021/07/10 15:16 ID: h4pizh9

I had a pretty tough time getting my 4x8GB 4000/CL15 B-Die (F4-4000C15Q-32GVK) to 3800RAM/1900I.F. stable on my 5900X/Dark Hero combo, I honestly wish I had went with the 3600/CL14 B-Die instead, but I enjoy overclocking so I wanted to give it a shot, plus running my current kit at a lower frequency should ultimately increase longevity. I am hoping for a BIOS update to possibly ease the process in the future, and have just done a stable 3600RAM/1800I.F. in the end. The knowledge about memory timings that I gained while trying to achieve higher memory frequencies and infinity clocks was well worth having the extra headroom to experiment however. In the end I would say a cheaper kit if you just want to get up and running, the higher speed kit if you want to adjust timings and see what you can squeeze from the chips.

10 : Anonymous2021/07/10 08:19 ID: h4ol1i9

2 sticks has better performance but i dont know about 4000mhz c18 vs 3600mhz c16. I think the 3600 c16 is gonna have better performance because then you can put the infinity fabric ratio 1:1 easier

ID: h4oqs4v

2 sticks has better performance

What? You're wrong.

ID: h4or6tn

If its dual channel, then 2 sticks is better than 4 because if you have 4 sticks then you have less bandwith per ram sticks

ID: h4onv9q

B-die costs 70$ more, Do you think it worths?

ID: h4ooyi6

+1 I have some gskill b dies and wondering if it was worth it

11 : Anonymous2021/07/10 08:49 ID: h4omu79

4800C18 is Hynix M die crap, go for 3600C16, it's probably Micron E or B die, much better.

12 : Anonymous2021/07/10 12:23 ID: h4p0wfp

I say get 2x16Gb sticks. I took 3600 and it needs set up in BIOS & I just use a very stable 3333Mhz.

You really are looking for a math genius, but need a chipst/mobo genius as you want to forget THE Crash and crash again setup junk TO HOLD your best timing IMHO.

13 : Anonymous2021/07/10 14:14 ID: h4pbo3h

4000 cl18, then overclock to 3800 cl 16 or 3600 cl 14


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