[SOLVED] Motherboard/RAM relationship ?

[vulka3]

Hi guys,

I have a question about the MB-RAM relationship. I'm planning on doing a system upgrade these days. I'll get the AMD 5900X CPU. Did my research and came to the conclusion that maybe Asus ROG Crosshair VIII Hero is the best MB for me (Please correct me if I'm wrong).

The problem is that when I did a comparison to the ASUS ROG Crosshair Formula VIII Hero here: https://versus.com/en/asus-rog-crosshair-viii-formula-vs-asus-rog-crosshair-viii-hero
It says that both MBs support up to 3200MHz RAM which is a bummer. because I wanted to use the G.SKILL Trident Z RGB 64GB (2x32GB) DDR4 4000MHz F4-4000C18D-64GTZR (Again, after doing my research for a good RAM).
Does that mean that in this case, I'll be buying expensive 4GHz RAM that will be bottlenecked to work with lower frequencies (3.2GHz)?
If so, could anyone recommend me a good MB that supports both the 5900X CPU and 4GHz RAM and has new-gen ports and lots of USB 3+ ports?

P.S: Also could anyone recommend me a CPU fan for the 5900X that's both good and quiet? (Not planning on doing any overclocking)

Thank you in advance!

 

[thx1138v2]

Take a closer look at the RAM specs and you'll see that 4000MHz is considered overclocking. As such, it's not guaranteed to work at that speed. It might. It might not.
https://rog.asus.com/motherboards/rog-crosshair/rog-crosshair-viii-formula-model/spec/

I'm not sure about the CPU but the following link says that CPU only goes up to 3200MHz but it doesn't say anything about overclocking.
https://www.amd.com/en/products/cpu/amd-ryzen-9-5900x

 

[Flayed]

With ram like that you can often run a lower frequency with much tighter timings. Plus if any board can OC ram the crosshair hero would be one of them

 

[vulka3]

I read about these timings and the actual RAM speeds. It turns out that the Trident Z mentioned above is 4000Mhz at CL 18. That means that its actual speed is exactly 9 nanoseconds. For comparison, any CL 16 at 3600 MHz equals to around 8.89 nanoseconds. The difference is negligible. The only 2 options I found that could be better (in my case) either CL14 at 3600MHz (7.78 nanoseconds) or CL18 at 4600MHz (7.826 nanoseconds). This last one is actually the current world record holder for speeds and OC and I don't need that.

I see that on AMD's website it says that 5900X and 5950X support up to 3200MHz but at the same time they say that it's best to use these CPUs with 4000MHz and above. I'm not sure exactly what's going on there, if this is some kind of marketing strategy or there's actually something more to it. IDK, maybe the fact that DDR stands for 'Double Data rate' and the CPU and MB state the SDR speed for some reason? Maybe it's all due to the I/O bus clock of DDR5 memory that's exactly 3200MHz.

 

[Flayed]

I read about these timings and the actual RAM speeds. It turns out that the Trident Z mentioned above is 4000Mhz at CL 18. That means that its actual speed is exactly 9 nanoseconds. For comparison, any CL 16 at 3600 MHz equals to around 8.89 nanoseconds. The difference is negligible. The only 2 options I found that could be better (in my case) either CL14 at 3600MHz (7.78 nanoseconds) or CL18 at 4600MHz (7.826 nanoseconds). This last one is actually the current world record holder for speeds and OC and I don't need that.

I see that on AMD's website it says that 5900X and 5950X support up to 3200MHz but at the same time they say that it's best to use these CPUs with 4000MHz and above. I'm not sure exactly what's going on there, if this is some kind of marketing strategy or there's actually something more to it. IDK, maybe the fact that DDR stands for 'Double Data rate' and the CPU and MB state the SDR speed for some reason? Maybe it's all due to the I/O bus clock of DDR5 memory that's exactly 3200MHz.

The offical maximum memory speed for the Ryzen 3xxx and 5xxx parts is 3200Mhz. Anything higher is therefore considered a memory overclock. People say to use 3600Mhz ram for the 3xxx parts for best performance. However, as you have said there are plenty of 3600Mhz with no so great memory timings and I'm not sure a 3600Mhz kit at CL18 or 19 is really any better than a 3200Mhz kit at CL14 or CL16.

I just use some 3200Mhz ram with my 3600 with CL16. It is perhaps not the best for performance but I am happy with how my system runs.

 

[vulka3]

So then that means that if I get the 5900X processor with the Crosshair VIII Hero MB which are both stated as 3200MHz and a RAM that say 3600MHZ then the only way to use this higher RAM frequency is for me to overclock both the CPU and the MB?

 

[Flayed]

So then that means that if I get the 5900X processor with the Crosshair VIII Hero MB which are both stated as 3200MHz and a RAM that say 3600MHZ then the only way to use this higher RAM frequency is for me to overclock both the CPU and the MB?

Well yes technically. Although all you would actually need to do is going into the bios and turn on xmp which is called dcop on Asus bios. This would set the memory speed to 3600Mhz and it should work