PC Processors

[iStephano]

Good day god folks. I’m sorry if this have been brought up 100x by now. But I am finally a happy owner of 7950x3d and I love it. So my instinct is ofc to be sure everything is okay. 

I have tested my system on stock settings for a week and thought about turning on expo. I can manually change my SOC to 1.2v but what concerns me is the CPU VDDIO/MC. 

It seems people are not talking much about it, my issue is I have G.Skill 2x32GB 6000mhz (F5-6000J3040G32GX2-TZ5NR) this kit is rated to 1.4v 

If I turn on expo my CPU VDDIO will boost up to 1.4v, so my question is, is this safe for the cpu?

My motherboard is MSI x670e Carbon wifi  

Thanks for all answers.

Edit: and what would you recommend?

[johnnyenglish · Accepted solution]

Hi, I did mentioned it before, in a video I made, lowered it as a safeguard soon after the "exploding cpu hype train" hitted us hard. Why? 

VDDIO MC also changes as soon as you enable EXPO.

And it makes sense because.. 

VDDIO_MEM is the voltage that is used to transfer data from between the memory controller and the DIMMs. By spec, it is supposed to be set to the same value as the DRAM_VDD/VDDQ voltages, so it should in theory be safe up to 1.4V

However.. Lower voltages are always better right? If it doesnt affect stability, i mean.

But something didn't add up. VDDQ was 1,35v and VDDIO MC was 1,4'toomuch. Not exactly the same value.

In fact, on AUTO both CPU SoC and VDDIO MC had the same values. So I tried both at 1,2v now 1,18v. I can run 6000mhz CL34 32gb G.Skil. No stability issues or errors at all! CL32 is also possible but I didn't had time to run an extended memtest stress.

I still cant get a solid explanation about this voltage but MC being Memory Controller, well... It kind of says it all.

I recomend lowering the value and stress test for stability issues. If ok, then its good to go!

Undervolting is now a common thing in the tweaking world. 

[johnnyenglish · Accepted solution]

Hi, I did mentioned it before, in a video I made, lowered it as a safeguard soon after the "exploding cpu hype train" hitted us hard. Why? 

VDDIO MC also changes as soon as you enable EXPO.

And it makes sense because.. 

VDDIO_MEM is the voltage that is used to transfer data from between the memory controller and the DIMMs. By spec, it is supposed to be set to the same value as the DRAM_VDD/VDDQ voltages, so it should in theory be safe up to 1.4V

However.. Lower voltages are always better right? If it doesnt affect stability, i mean.

But something didn't add up. VDDQ was 1,35v and VDDIO MC was 1,4'toomuch. Not exactly the same value.

In fact, on AUTO both CPU SoC and VDDIO MC had the same values. So I tried both at 1,2v now 1,18v. I can run 6000mhz CL34 32gb G.Skil. No stability issues or errors at all! CL32 is also possible but I didn't had time to run an extended memtest stress.

I still cant get a solid explanation about this voltage but MC being Memory Controller, well... It kind of says it all.

I recomend lowering the value and stress test for stability issues. If ok, then its good to go!

Undervolting is now a common thing in the tweaking world. 

[iStephano]

Hi

Thank you for a good long explanation of this topic. And thanks for the video! I did watch it and I understand what you mean and the logic behind it. As a safeguard it seems only the best option to do yea. I will try to lower it myself as you did and hope it’s stable with okay enough timings on the Ram. 

It helps me relax a bit more knowing this information so thanks again!  

[johnnyenglish · Accepted solution]

Thank You for the kind words.

[iStephano]

Just wanted to give you a little update, since you took the time to answer me.

So after many days with testing and changing settings with stress test one after each-other I landed on this. 

SOC: 1.2v 

CPU VDDIO 1.25v 

My 64GB kit is running 6000mhz (30-40-40-28) with Buildzoids timings (from another YouTuber) and to my surprise I think I hit the sweet spot! I even got higher score in 3DMark and my Ram latency is 63ns 🤯 It blows my mind that lowering the voltages actually gave me better score and ofc the timings helped a lot. After so many bugs and frustration with EXPO I just decided doing it manually, and it works so smooth now. 

Good performance and safe voltages was all I wanted ^^