I stumbled upon this thread as I have been experiencing the same thing. While browsing this forum, I noticed this sticky: https://rog.asus.com/forum/showthread.php?90663-Kaby-Lake-overclocking-guide
Skimmed through it and on page 3 I read this:
I was like ok, never really tinkered with these and I've got nothing to lose. I did a cold boot with a 4.7 OC, manual timings, and VCCIO/SA voltages on Auto. No POST. Did my tried and tested revival method by unplugging the power cord, hit the power button a few times, plug it back it and power it back on. Pressed F1 and decided to put to 1.1V on both (actual values 1.12 VCCIO, 1.128V SA) as the OC guide suggests for the minimum. My memory is a Corsair Vengeance LPX DDR4 3000 2x 16GB (CMK32GX4M2B3000C15W) rated 15-17-17-35 timings @ 1.35V.
Cool, it booted. Then I thought, what if I changed it a bit. How high or low can I go? I hit the + button while at 1.1V on both and it had an input of 1.11250. Saved changes and sure enough gave me a RLOD. This is what it looked like after the reset:
Notice it said 0.968V VCCIO and 1.072V SA, I was like what if I put these values? Again using + on the keyboard, I went as close to these values as possible with having a bit more instead of less:
It booted, although I noticed the amber light stayed lit for like 3 seconds before it finally went through. So at this point I wanted to try the lowest values for both. From Auto, pressing the + sign resulted to 0.9V VCCIO and 0.7V SA. This time the LED was a solid amber.
So I figured out the lowest (0.975V input/0.992V-1.0V actual, this value was changing back and forth in real time) and highest VCCIO value I could go (1.1V input/1.12V actual). The SA on the other hand has a bigger room for error. An input of 1.0 to 1.2 booted no problem. Didn't test any higher than 1.2 though. It would've probably still booted at 1.3V.
Going back to the chart in the beginning, I'd like to stay at these values as close as possible on 3000mhz. I settled at 1.0625V VCCIO (1.088V actual) and 1.125V SA (1.152V actual).
As mentioned earlier ITT, this mobo needs a BIOS update to fix/stabilize the Auto setting for the VCCIO and SA, particularly VCCIO, as it has a smaller room for error. Maybe that explains why sometimes the system will boot and sometimes it doesn't. I need to read up more on this and find out where the author got those values from. For now, these are 100% stable. I'll report back if I see the RLOD again.
Skimmed through it and on page 3 I read this:
Apply changes, then retest for stability. Also be sure to check the system can POST consistently from a power cycle and warm restart. Memory training occurs during these periods, and if these voltages haven’t been tuned properly, it will result in the system being unable to POST or BOOT.
I was like ok, never really tinkered with these and I've got nothing to lose. I did a cold boot with a 4.7 OC, manual timings, and VCCIO/SA voltages on Auto. No POST. Did my tried and tested revival method by unplugging the power cord, hit the power button a few times, plug it back it and power it back on. Pressed F1 and decided to put to 1.1V on both (actual values 1.12 VCCIO, 1.128V SA) as the OC guide suggests for the minimum. My memory is a Corsair Vengeance LPX DDR4 3000 2x 16GB (CMK32GX4M2B3000C15W) rated 15-17-17-35 timings @ 1.35V.
Cool, it booted. Then I thought, what if I changed it a bit. How high or low can I go? I hit the + button while at 1.1V on both and it had an input of 1.11250. Saved changes and sure enough gave me a RLOD. This is what it looked like after the reset:
Notice it said 0.968V VCCIO and 1.072V SA, I was like what if I put these values? Again using + on the keyboard, I went as close to these values as possible with having a bit more instead of less:
It booted, although I noticed the amber light stayed lit for like 3 seconds before it finally went through. So at this point I wanted to try the lowest values for both. From Auto, pressing the + sign resulted to 0.9V VCCIO and 0.7V SA. This time the LED was a solid amber.
So I figured out the lowest (0.975V input/0.992V-1.0V actual, this value was changing back and forth in real time) and highest VCCIO value I could go (1.1V input/1.12V actual). The SA on the other hand has a bigger room for error. An input of 1.0 to 1.2 booted no problem. Didn't test any higher than 1.2 though. It would've probably still booted at 1.3V.
Going back to the chart in the beginning, I'd like to stay at these values as close as possible on 3000mhz. I settled at 1.0625V VCCIO (1.088V actual) and 1.125V SA (1.152V actual).
As mentioned earlier ITT, this mobo needs a BIOS update to fix/stabilize the Auto setting for the VCCIO and SA, particularly VCCIO, as it has a smaller room for error. Maybe that explains why sometimes the system will boot and sometimes it doesn't. I need to read up more on this and find out where the author got those values from. For now, these are 100% stable. I'll report back if I see the RLOD again.
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