Safe VCCSA and VCCIO for DDR4

emil2424 wrote: hi My PC Intel Core i7 6700K + Thermalright Macho Rev. B Asrock Fatal1ty Z170 Gaming K4 Zotac GeForce GTX 1080 AMP! Extreme G.Skill TridentZ DDR4 XMP 3200 MHz 2x 8GB (F4-3200C16D-16GTZ) GoodRAM Iridium Pro 240 GB WD Red 2TB EVGA 750W SuperNOVA G2 Asus Rog Swift PG348Q (3440x1440) Nzxt H440 Windows 10 Pro x64 With the started XMP profile (16-16-16 -35-2 N 1.35 V) the PC isn't being started. I tried to lower the frequency and to change voltages (1.25-1.4). But only what helped it is a VCCSA change 1.050 - > 1.07 and VCCIO 0.95 - > 1.02 but not yet I carried of more serious tests of the stability. My question is following: what VCCSA values and VCCIO are safe for DDR4 and the Skylake platform

Finally found your thread again, I meant to reply earlier.

The VCCSA set to 1.07V and VCCIO set to 1.02V are both very safe voltages to use.

But those are the voltages you set them to, correct? Did you check the H/W Monitoring screen to see what the actual, resulting voltages are?

The same is true for the DRAM voltage, the setting may not match the actual, resulting voltage.

Intel does not provide maximum values for the VCCIO and VCCSA voltages in their Skylake processor document. The values you saw in the UEFI of 0.95V and 1.050V, are what Intel calls the Typical, or standard values.

What a "safe" value for either of these voltages is, does not have a simple answer.

If you go to those options in the UEFI, and press the + or - keys, the value will change. When pressing the + key, at some point you'll see the value displayed in red text, which indicates a high value that should be used with caution, or not used at all. You should find that your current values for those voltages are below the red values.

If you were able to use the XMP profile, which don't work well for me with my TridentZ memory, but simply select the XMP profile and then check the resulting VCCIO and VCCSA voltages, you should find them to be very high. This also happens when those voltages are set to Auto.

At a speed of 3200, my TridentZ memory had an Auto VCCSA of 1.280V, and an Auto VCCIO of 1.180V. I can (and do) reduce them to much lower values, but not as low as yours. I have a different model of TridentZ.

emil2424 wrote: I managed to achieve the stability (1 h in RealBench and AIDA64 Extreme) for the value: VCCIO = 1.09 V VCCSA = 1.07 V H/W monitor in UEFI: VCCIO = 1.120 V VCCSA = 1.088 V If in the future I will experience the instability of the system I just will increase VCCIO and VCCSA  +0,01 and try some tests. What's interesting VCCIO and VCCSA set on "auto" report in H/W monitor much higher values, as similarly as at You (~1.280V, ~1.180V) but the PC even didn't start. So in case of  RAM more voltage doesn't mean the greater stability?

That is exactly right, for VCCIO and VCCSA. The main DRAM voltage is not like those two, at higher speeds, more DRAM voltage is always needed.

But the "right" voltage for VCCSA and VCCIO is different for different models of memory, and probably the CPU being used. Usually high VCCSA and VCCIO voltage is fine for most DDR4 memory, but that seems to be changing now.

The memory controller is part of the CPU, and just like different examples of the same CPU model can over clock better or worse, the memory controller can be different. Intel only guarantees a Skylake CPU can run DDR4 memory at a speed of 2133. That is also for 64GB of memory.

You saw how the actual VCCIO and VCCSA voltage is higher than the value you entered for each of them. The same is true for the DRAM voltage, at least on my board.

Normally, VCCSA needs to be more than VCCIO, so you should be able to set VCCIO lower than you have it now.

My G.SKILL TridentZ memory is the GTZB model. It works with VCCIO at 1.180V and VCCSA at 1.280V, which is what Auto does on my board.

I have VCCIO at 1.128V and VCCSA at 1.160V now, but I've had it lower than that. I doubt this memory would boot at the voltages yours does. I can try it, but I don't think I've ever had the VCCSA below 1.15V.

I set manualy DRAM Voltage to 1,35V and in H/W i see 1,36V. Under the automatic mode for DRAM the real value was 1.36 V.