HyperX CL17 fallback to CL18

[macedot]

I was fortunate enough to upgrade my old i5-4690k rig last month and everything seems to be working fine except memory CL.

 

Rig now runs a 5900x + X570 AORUS ULTRA (F33h) + HyperX 4x8GB (HX436C17FB3K4/32 , https://www.kingston.com/datasheets/HX436C17FB3K4_32.pdf).

 

First XMP profile was supposed to set 3600-CL17@1.35v but it fallbacks to 3600-CL18@1.38v, as per motherboard report. I can't figure it out why... I event tried to force CL17 alongside other params directly on timing section on bios with no success.

 

Aida32, indeed, does report it as CL18 compatible (see pict) but it should be CL17 capable, doesn't it?

I doubt it would unfold in a huge difference but hey, it said Cl17 on the sheet

 

Thanks in advance!

[Skiiwee29]

There is a setting in the memory stuff, I think its Gear down mode? Could be wrong, but it will round it up to an even number. 

[macedot]

6 minutes ago, Skiiwee29 said:

There is a setting in the memory stuff, I think its Gear down mode? Could be wrong, but it will round it up to an even number. 

wow, never head of it! gonna google a bit. thx mate!

 

EDIT: seems on point! gonna leave some links here for future reference
https://forums.tomshardware.com/threads/ryzen-overclock.3574574/#post-21591024
https://community.amd.com/t5/blogs/memory-oc-showdown-frequency-vs-memory-timings/ba-p/415729

 

EDIT2: on that case should I try 1696 with CL16 then? will it matter, anyway?

[Skiiwee29]

20 hours ago, macedot said:

wow, never head of it! gonna google a bit. thx mate!

 

EDIT: seems on point! gonna leave some links here for future reference
https://forums.tomshardware.com/threads/ryzen-overclock.3574574/#post-21591024
https://community.amd.com/t5/blogs/memory-oc-showdown-frequency-vs-memory-timings/ba-p/415729

 

EDIT2: on that case should I try 1696 with CL16 then? will it matter, anyway?

You can always play around and try tightening up your timings to see what you can achieve. Just remember though, in general, you want to keep things in a 1 to 1 ratio between the Memory clock and the Fclock, so 3600mhz is probably the fastest, though early testing by Anthony did yield some interesting results on Ryzen CPUs. You can see that video here: