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bigbeard · ‎11-09-2018

I have a 32gb kit from gskill that is guaranteed to work at 4000mhz. the kit is verified to work by both gskill and asus. My mobo (z390 hero wifi) is giving me problems at that speed. Sometimes the pc will boot fine, but other times the pc will repost and memOK will run, and push my vccio and SA voltage up to 1.35 and 1.4, respectively. This is unsafe, is it not? if I downclock to 3900mhz on ram, I was use 1.1v vccio and 1.15SA. But again, once every few powerups (but less often) memOK will push 1.25v on each.

I ram memtest and my ram is 100% fine. It seems like the mobo has some kind of problem when powering on and having the ram work. What can I do to fix this?

markuaw1 · ‎11-09-2018

i have a ROG MAXIMUS X HERO, and run my G.Skill Trident Z RGB 16GB -3600 Memory at 4000mhz with CL17/18/18/38 settings with 1.1v vccio and 1.15SA stock 1.35v setting and it runs great never have any problems with it

Silent_Scone · ‎11-09-2018

The POST failures are due to memory instability. You may want to try Maximus Tweak Mode 2 in this instance.

You can enable MRC Fast Boot, however, I would recommend trying to get the system to pass POST consistently, instead.

13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

HiVizMan · ‎11-10-2018

Each CPU has a unique IMC (memory controller) and the ram has been tested to run those stated frequencies by GSkill. Your CPU may however not have the strongest IMC - mine is very weak for example but I can boot into 56x on water with no real effort at all.

So you may find that you have to relax some settings if you wish to run at those stated frequencies. Personally I would see what the difference in performance is in relation to tighter timings v higher frequency and go with which ever gives me that edge in performance.

To help us help you - please provide as much information about your system and the problem as possible.

Silent_Scone · ‎11-10-2018

Another point worth mentioning is the inclusion of two XMP profiles this gen. Mode I and Mode II.

Mode I - ASUS Timings

Mode II - XMP Timings

Mode II will often have looser memory subsets, so be sure to try this, too.

13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

bigbeard · ‎11-10-2018

thanks for all the replies.

strangley, I got the system stable (so far) at 4000mhz ram with tighter timings (cas 17), increased dram voltage (1.4) and vccio at 1.15v and SA at 1.2v.

Something must have change during the many re-posts the pc was doing. may changed some secondary timings that wasn't working?

Silent_Scone · ‎11-10-2018

bigbeard wrote:
thanks for all the replies.

strangley, I got the system stable (so far) at 4000mhz ram with tighter timings (cas 17), increased dram voltage (1.4) and vccio at 1.15v and SA at 1.2v.

Something must have change during the many re-posts the pc was doing. may changed some secondary timings that wasn't working?

many things can contribute to training failure (temperature, RTL/IOL, signal alignment), you’ll need to soak test the system across multiple power ups. If you still experience the odd failure to POST, you can enable MRC Fast Boot in order to retain training in NVRAM.

13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

HiVizMan · ‎11-11-2018

The setting of Cas17 will have had some knock on effect with other timings that you do not have access too. That automatic process may have resolved an un-identified issue that was preventing posting.

Just enjoy mate.

To help us help you - please provide as much information about your system and the problem as possible.

9900k, ddr4 speed, vccio and sa