Z170 Pro4S Ram OC problem

So I have just built a system using AsRock Z170 Pro4S (CPU: i5 6500) and after unsuccessful attempts to overclock my ram, I decided to look for help here.
Firstly, I understand that there are no guarantees when overclocking.
RAM Kit: DDR4 Crucial Ballistix Sport LT 2400 MHz 2x8GB (16-16-16-39, 1.2V)

I specifically bought this ram kit expecting to OC it to at least 2666MHz, especialy since reviews show that this ram is capable of reaching 2800MHz+.

RAM runs with no problems at stock speed, I even reduced timings to 12-12-12-31. I'm also able to overvolt RAM or underclock it without problems

However I'm unable to overclock it by any amount, system simply won't post afterwards.


Edited by Soft Brick - 24 Jan 2016 at 1:28am

I've tried these settings:
VCCIO: 1.2v
VCSSA: 1.35v (max allowed)
RAM Voltage: 1.3v

But I'm still unable to reach even 2533MHz.

I tested SkyOC just to see if it actually works. I ran some benchmarks @4.51GHz 1.325v, without any fine tuning or stability testing. And of course I had to keep my ram under 2400MHz. 
Average performance gains were about 30%, which is really nice. 



Edited by Soft Brick - 22 Jan 2016 at 5:40am

http://i.imgur.com/5ywacFr.png?1

Managed to boot at 2533MHz, I'll update..

Update:

1.4v on RAM allowed me to boot at 2533MHz (16-16-16-39): http://i.imgur.com/Lnyu2CA.png?1

No boot at 1.35v (2533MHz)
No boot when i set 15-15-15-36 timings (1.4v)(2533MHz)
No boot 2666MHz, 1.4v, 16-16-16-39

Edited by Soft Brick - 22 Jan 2016 at 7:42am

You should set all the timings to Auto when you increase memory speed, if you prefer to have the PC boot more likely than not. Yes the timings will be very high on Auto, but at least you know the speed is possible.

I suggest checking the memory voltage with a third party program. My ASRock Z170 board produces about 0.015V more than the setting displayed in the UEFI.

I have my cheap Crucial 2133 DDR4 (not even Ballistic Sport) in my X99 board running at 2666, with the 2133 timings, by some miracle. That's even with mixed kits and six DIMMs in a quad channel board.

UPDATE:

So update 3.00 just got released and I immediately flashed it.
Sadly however, problem still persists.

This update brought an interesting feature. By pressing X on bios splash screen you can activate SkyOC function, which automatically overclocks CPU slightly (BCLK -110) and bumps voltage +100mV. CPU runs at 3.52Ghz (stock 3.2GHz). CPU temps are still at "100C" however.
Funnily enough, this feature also overclocks ram to around 2660, and of course I am not able to boot unless I underclock it to around 2350.



Edited by Soft Brick - 22 Jan 2016 at 8:03pm