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OC I7 6700k + 3200 C15 DDR4 on ASUS Z170 : Issues RAM + CPU

Hi Guys,

After several attempts, it seems time for me to ask for your help !

First of all, hereafter my build :
> I7 6700k
> ASUS Z170 Pro GAMING with latest UEFI v1901
> G Kill Trident Z 32Go (16*2) 3200 Mhz CAS 15
> ASUS GTX 1070 ROG O8G
> High End Air Cooling : Be Quiet Dark Rock Pro 3
> Windows 7 Pro

First Step: Get XMP set for DDR4 : Not achieved
The max freq i've been able to reach is 3100 Mhz. No boot with 3200 Mhz set.

Second Step: OC CPU
> 1.35 V / 4.6 Ghz / LLC 5 : Boot but didn't passed the stress test (RealBench)
> down to 4.5 Ghz : Boot and passed the stress test. However, temp did reached 85 °C.
> Last try were : 1.31 V / 4.5 Ghz / LLC Auto : Temp 80 °C

Getting back and out of the UEFI a few times and throug monitoring, I did noticed that voltages do exceed values as manually set.
Example :
> VDRAM set at 1.35 V (as XMP) / it ends up after stress test at 1.368V (the 1.35 are shown in pink color)
> Same for VCPU : set at 1.31. HWMonitor records Voltage up to 1.4V during stress test.
Is this normal/safe ? If it's fluctuates that much, how reliable is the value we set ? Is it considered as the values in idle ? I guess the fluctuation is linked with LLC : what set shall be used ? LLC 5 or LLC 4 or Auto ?

So for DDR4 :
How can I reach 3200 Mhz ? : Shall I play with VCCIO + SAV ? What are max safe volt ? I guess MEMTEST will be required, realbench not being relevant for DRAM.
If not achievable, is 3100 Mhz fine (3100 freq not being sold, by the way. It's either 3000 Mhz or 3200 Mhz) ? should i get down to 3000 Mhz for "safe/efficiency" reasons ? Do 3200 Mhz downgraded to 3100/3000 Mhz performs as well as basic 3000 Mhz kits ?

For CPU:
4.5 Ghz seems to be the sweet spot for me. 4.6 Ghz will need to reach 1.35V+ which raises to much temp.
What about this voltage fluctuation matter ? What LLC value ?

As you might have noticed, i'm not an expert in overclocking, so i shall rely heavily on your advices. Please keep it simple :)
Thank for reading me and for your help!!
3 answers Last reply Best Answer
More about 6700k 3200 c15 ddr4 asus z170 issues ram cpu
  1. Load BIOS defaults, then have one module installed, enable XMP, and see if both perform the same.

    If each can work fine at 3200, together they should be capable. You may need to set VCCIO and VCCSA around +0.1V Voltage to work properly.

    VDRAM and VCPU slightly higher is fine. That is normal especially under load. The set value is always slightly different than supplied value, so you need to test and see what is best.

    LLC on AUTO is fine

    If 3100 is your maximum, that is fine. You can raise Voltage or timings to maximize performance. 3200 is a better chip, so you can achieve better results than a 3000.
  2. Hi,

    Thx for the reply.

    I made the test by rebooting with only one module. Tried to pump voltage at 1.25 VCCSA / 1.2 VCCIO. It makes no difference...
    Seems like 3100 Mhz is my upper limit. Cannot figure why...

    However, through tweaking in UEFI I end up with new settings :

    As mentioned yesterday, 4.5Ghz looked like the sweat spot.
    However after 1h REALBENCH 2.43 stress test, temp went up to 85 C... with 1.32V... which is as i understand to high.

    After downclocking at 4.4 Ghz I started to play with BCLK...
    It seems like i found kind of an alternative path :
    44 Core Ratio * 102.5 BCLK = 4.51 Ghz
    Min Core cache = 4.2Ghz
    DDR4 = 3075 Mhz
    VCORE set at 1.315V
    FCLK = 1025 Mhz
    Realbenck for 4 h : highest temp was 81/80/80/81 and average at 76/77 C. Ambient temp were around 26 C.

    Questions :
    _ As my ambient temp can reach 30 C (+4 C) is the temp achieved with realbench a good to go ?! Or shall I get down to a BCLK of 102 for peace of mind ?
    _ Messing with BCLK, changed the way freq is achieved and power distributed, are the new values/effects on DRAM, FCLK and core cache OK ? Have I something to worry about ?
    _ Might give a try with 3143 Mhz DDR4 as the option is available...

    Anyway, reaching 4.5 Ghz through BCLK for the last 100 Mhz, with 44 CPU Ratio, did worked better for me (from temp perspective at least) than std BCLK + 45 CPU Ratio

    Thanks a lot in advance for your help!
  3. Best answer
    Just make sure CPU temp does not exceed 80C under max load, which should not be a problem even ambient 30C

    Those settings should be fine, so as long as the system is stable you are good to go.

    Keep us posted!
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