10900KF, Gaming-E Z490 and 4000Mhz DDR4

[Gunny Cassidy]

Hi,

I just got ROG Gaming-E Z490 combined with 10900KF and to my surprise, system does not boot with XMP profiles (never happened to me before). I think it fails some BIOS test. Memory is G.Skill F4-4000C19D-32GTZR 2x16Gb installed into A2 and B2 as recommended in the manual.

I tried bumping SA/IO and DRAM voltages, but the best I can get is 3100Mhz. Which is quite disappointing, because this memory was way more expensive than 3200Mhz, and my previous 8700K ran 3200Mhz on cheapo motherboard no problem. Am I out of luck and there's nothing I can do to make it run at XMP 4000Mhz or at least higher than 3100Mhz?
Also tried:
MCR Fast Boot: enabled
Round Trip Latency: enabled
MCH Full Check: disabled

And, couple more questions:

* While playing with settings, sometimes 3200Mhz will get accepted and boot stable. But I can't set it anymore, any ideas why?

* What is the best way to save my overclock settings before updating the BIOS?

* And performance question. With Heaven Benchmark 4.0 I get 10% higher score if all cores are at 5.1Ghz rather than 3x5.3Ghz, 3x5.2Ghz and 4x5.1Ghz. No throttling. Why would perf be slightly higher with all cores at 5.1Ghz? I understand it is test specific, and elsewhere I get higher scores with the second setup, just curious.

Cheers!

[Arne Saknussemm]

I tried bumping SA/IO and DRAM voltages

Hi there...what voltage have you tried?

1.45 DRAM 1.3 SA and IO? Some of these CPUs are plain bad to get higher than 3600 on...

The last part you answered your own question I think LOL

[Gunny Cassidy]

Hi there...what voltage have you tried?

1.45 DRAM 1.3 SA and IO? Some of these CPUs are plain bad to get higher than 3600 on...

The last part you answered your own question I think LOL

Thanks Arne. I tried up to 1.45 DRAM and 1.4 SA/IO - no dice, it won't move up from 3100Mhz.

The consolation here is that 3100Mhz is already above 2933Mhz stock, and I got decent timings 13/13/13/34, but just an unpleasant surprise.

[Arne Saknussemm]

Hmm...I have to say that is a pretty bad result...

I wonder what happens if you test one RAM module at a time? swingle stick at a time....I mean, not that there's one dodgy stick or something....

[qlfenv]

You don't have to change dram voltage or up vccio or vccsa. Reset these too to default: MCR Fast Boot: enabled Round Trip Latency: enabled, MCH Full Check: disabled.
The only thing you have to do is play with rtt_park values for channel a and b. These 2 settings are found under dram timings menu>skew control. If you have dual rank modules set those to 240 clocks and if you have single rank modules to 120. Set the vccio and vccsa voltages to 1.25 both. There is no way you need more than that for 4000 memory.

[Gunny Cassidy]

You don't have to change dram voltage or up vccio or vccsa. Reset these too to default: MCR Fast Boot: enabled Round Trip Latency: enabled, MCH Full Check: disabled.
The only thing you have to do is play with rtt_park values for channel a and b. These 2 settings are found under dram timings menu>skew control. If you have dual rank modules set those to 240 clocks and if you have single rank modules to 120. Set the vccio and vccsa voltages to 1.25 both. There is no way you need more than that for 4000 memory.

Thanks - tried that but it did not amake any difference. System won't boot at anything above 3100Mhz.

I think the next step is to try single module. Also hoping ASUS BIOS update will improve compat here.

[lassek]

Hello there.. I have the same problem.. please see my thread here:

https://rog.asus.com/forum/showthrea...sed-3600-speed

Did you ever find a fix?

[Shadowdane]

I ran into issues with high clocked kits DDR4-4000 on my i9-9900K and found setting the Initial BCLK to 99.9Mhz got it booting up just fine. This makes it so on the initial portion of the boot when the system is doing memory training it's running at 99.9Mhz. Once memory training is completed it will set the final BCLK value. Also make sure the regular BCLK value is set to 100.000Mhz though in the BIOS. Set it manually make sure it's not Auto.

I noticed this could be an issue as a few times I tried slower memory speeds DDR4-3000 and found on bootup it was actually giving me 104Mhz BCLK for some reason with that set to Auto. That high of a BCLK throws your memory clock significantly higher than the rated speeds.

100Mhz x 15 Ratio = 1500Mhz x 2 = 3000Mhz Memory
104Mhz x 15 Ratio = 1560Mhz x 2 = 3120Mhz Memory (120Mhz overclock)
100Mhz x 20 Ratio = 2000Mhz x 2 = 4000Mhz Memory
104Mhz x 20 Ratio = 2080Mhz x 2 = 4160Mhz Memory (160Mhz overclock)

That higher BCLK was causing the system to fail booting on higher speeds as the higher the ratio the bigger overclock you'd actually end up getting.

[lassek]

I am only able to get 3333 mhz stable at 16-16-16-36 2N .. ram is advertised to 3600 ..