VDD VDDQ voltage issue

[Benoit31]

Hello,

Can you explain to me this strange thing please :

My setup :

Core i7 14700k/asus z790 a prime

128Go DDR5 (4*32Go)

RAM settings :

Frequency : 5200 mhz / CAS : 40-40-40-80

VccSA : 1.1 V / memory controler : 1.25 V / VDD : 1.1 V (auto) / VDDQ : 1.1 V (auto)

It seeam stable, y-cruncher 3 VT3 passes (need more long test)

But when i set VDD and VDDQ to 1.25 V windows crash at boot and bios lag. Why this settings do that whereas it should help RAM stick to works ? Don't understand...

I spent much time to understand. I have left to auto all settings to begin, set manually settings after one per one to find it.

[achugh]

Why are you trying to set the memory settings manually? Have you tried to use the XMP profiles available to get the rated speed of your memory?

[Silent_Scone]

More voltage doesn't always equate to "better" stability. As is the nature of signalling...

What's the memory kit part number?

[Benoit31]

Hello,

To start with I bought a first 2x32go kit. I then wanted to upgrade to 128GB a few months later. I bought exactly the same kit.(but PMIC chip is different...)

 I didn't know that I shouldn't mix kits and that 4 dimm was more complicated to run...

So, its why i cant simply set xmp without manual settings.

What i have tried :

XMP2 downcloak @5200mhz (6000 by default), auto settings :

VccSA : 1.3V / memory controler : 1.4V / VDD and VDDQ : 1.4V

Seeam to run stable but voltage à bit high for me.

Other test :

I set timing to CL40-40-40-80 and VccSA : 1.25V

Set memory controler / VDD / VDDQ to 1.25V => crash/unstable

Set memory controler to 1.25V.

VDD VDDQ to 1.1V  => seeam to run stable ...

So, if i want to set 1.25 to VDD and VDDQ, it seeam i need to increase memory contrôler voltage also. Is there a link between them ?

[Silent_Scone]

Yeah, unfortunately, help vicariously when mixing kits isn't easy. It requires a reasonable understanding of what the voltage and timings do..

Yes, IMCVDD will need to scale for higher density and frequency. The auto rules will scale, but manual tuning may be needed.  

The XMP2 setting you've adjusted seems fine, nothing wrong with those voltages. You'll just need to see where that kit is happy to run. Worst case, you can simply back off the frequency.

[Benoit31]

Ok, but i dont understand, at same frequency 5200 mhz why that :

IMCVDD : 1.4V / VDD : 1.4V / VDDQ : 1.4V => OK

IMCVDD : 1.25V / VDD : 1.1V / VDDQ : 1.1V => OK

IMCVDD : 1.25V / VDD : 1.25V / VDDQ : 1.25V => NOT OK