DDR4 Overclock adventure, sort of...

[Nenu]

A year ago I bought a Z170 system with 4x4GB Corsair Vengeance LPX 3000 C15. Kit name: CMK16GX4M4B3000C15

In my first mobo, MSI Z170a Gaming Pro, it barely ran at default 3000MHz speed.
A later ASRock Z170 Extreme 4+ had similar problems.
On both boards with certain BIOS versions I could use it for gaming at rated speed but it failed testing.
Anything that needed the CPU at full pelt I had to slow it down to 2800MHz for stability.
Other BIOS versions knocked it down to 2500MHz max.
Manual settings got it rock stable at 2800MHz with certain BIOS versions, nothing faster.

I got an RMA from Corsair but didnt take them up on it.
They offered to replace the 4x4GB with the equivalent 2x8GB.

I eventually got an Asus Maximus VIII Hero Motherboard and at last was stable at default XMP 3000MHz but it wouldnt clock any higher.
That was in March.
I considered the RMA again today because the memory is advertised as being good for overclocking so decided to try clocking it again.

This has been one of my simplest clocking experiences.
A few times I had to press the mobos get out of jail free button when using too low a timing but it didnt once crash while booting or when in Windows.
This ram which could barely run at default speed before now clocks to 3733MHz in the new board and I can game fine with it. At default 1.35V as well !!
I didnt try hard to get it fully stable at 3733MHz because the timings seemed a bit too high so I backed off to 3600MHz with this final result:

1.35V 3600MHz 19,20,20,42 and tRFC = 480
Thats 20% higher clock speed and slightly higher timings than shop bought 3600MHz ram, result!
Default:
1.35V 3000MHz 15,17,17,35 tRFC less than 300 - forgot to write it down

I decided to see what this would do with my clocked 980ti, 6700K @ 4.6GHz.
Practically jack all lol.
Games, no benefit at all. Password cracking (yeah I forgot one), no benefit.
Windows is a bit snappier and new connections over broadband are made a lot faster. I use Peerblock and the speed which connections whiz up the screen is significantly faster.
Neither was a problem before, so no real advantage.

So there you have it, some crap ram isnt so crap and clocks like a nutter in the right motherboard/bios.
But theres not really much point going beyond 3000MHz.

 

[dasa]

nice going with that oc and thanks for sharing your experience with different mb

i bet you will find that there is no difference between cpu stock vs overclocked in those games ether only from gpu oc
but in any cpu limited games the higher ram speed could be as important if not more so than the cpu oc

i recently upgraded to a 6700k and ran some tests on my 3200c14 kit managed to get it stable at 3866c16 1.425vdim 1.25v sa 1.2vtt

average fps in fallout 4 are not all that accurate but the min fps are

your typical gpu bottlenecked game

 

[Nenu]

Nice going with your overclocks!
When I bought my ram, there wasnt much choice, same with motherboards.
I would have liked low CAS ram like yours. I tried hard to get some GSKill Ripjaws V but it didnt appear in the UK for a long time.
Nice info you posted.

My inner overclocker wonders if I could lower my timings with higher voltage.
My ram runs cold at 1.35V overclocked and this new mobo had it running at 1.5V auto for a while after updating to the latest bios, with no damage.
It looks like it can cope with quite a bit higher.
I havent tried adjusting SA or VCCIO yet because it just kept working without, I might have some luck with those. Although I've read for some that too high, even at lower voltages, can lead to instability. It can have a narrow window.

I looked up how much quicker Fallout 4 would run from a few benchmarkers results and reckon about 4% max for me.
It appears to help SLI users up to 15% for the reason you suggested, due to the extra CPU overhead with SLI on CPU bound games.
Nothing I play struggles being on 1080p 60Hz so pushing the boundaries would be just for fun.
Your 3000 C12 results are quite nuts, I guess low CAS really helps FO4 and Arma III.

I forgot to set CR = 1, cheers for the reminder.
ps
The 2 images with ?attredirects=0 tagged on the end dont display.

 

[Nenu]

Tried CR = 1. No go, not even at 1.45V

At 1.395V managed to get 3600MHz 17,20,20,41 down from 19,20,20,42. tRFC is still at 460.

SA voltage is already at 1.288V when left on auto. Its set this high even at 2133MHz. VCCIO is also very high.
This is waaay into the red so I dont want to push any harder.

 

[dasa]

sounds like that mb is fairly heavy on the auto v i like to keep things in the yellow maybe pink if i can and well out of the red for 24\7 use
with upping the v for the ram the biggest risk is to the cpu i believe
v sa\vtt are for the memory controller and would have helped more with your older mb

nice drop in latency from a little extra v to the ram
since your sa vtt are already rather high i would try manually lowering them and see if you lose any stability

im not running CR = 1 for my 24\7 oc as it was failing the HCI stress test
didnt seem to make much difference to performance anyway tightening the other sub timings gained more than was lost by setting it to 2

your performance in fallout 4 with a single gpu will depend on the part of the game your in in some parts you will see ~20-30% gain vs 2133 in others you will see 0%
so the higher ram speed will bring you more consistent fps by improving performance in parts of the game where you would have dropped rather low
unless your running 4k then you may just be completely gpu bottlenecked everywhere

its not really cpu overhead from sli its just the higher gpu performance is reducing the gpu bottleneck which shifts to cpu bottleneck

ah ok i will fix the links
working now with ?attredirects=0 removed? it was just a system image and fallout4

the ram is still not really available in au its about twice the price that it is in the us in the few stores that list it so i imported it and the gtx1070 from newegg

i found the info here very useful for tweaking and the tests great for finding problems with stability
[Official] Skylake, Haswell-E & Broadwell-E 24/7 DDR4 Memory Stability thread

 

[Nenu]

sounds like that mb is fairly heavy on the auto v i like to keep things in the yellow maybe pink if i can and well out of the red for 24\7 use
with upping the v for the ram the biggest risk is to the cpu i believe
v sa\vtt are for the memory controller and would have helped more with your older mb

Yeah it is odd.
Even when VSA and VCCIO are manually set to 1.23V, they both reach up to 1.28V or even 1.304V
Only when set below 1.23V do they start dropping sensibly.
I managed to get stable at 1.15V which reads as 1.2V.

nice drop in latency from a little extra v to the ram
since your sa vtt are already rather high i would try manually lowering them and see if you lose any stability

Yep, had fair success.

im not running CR = 1 for my 24\7 oc as it was failing the HCI stress test
didnt seem to make much difference to performance anyway tightening the other sub timings gained more than was lost by setting it to 2

I've always been able to run this ram at CR = 1, even when it couldnt clock.
I had a hope it would work now I'm clocking well but nada.

your performance in fallout 4 with a single gpu will depend on the part of the game your in in some parts you will see ~20-30% gain vs 2133 in others you will see 0%
so the higher ram speed will bring you more consistent fps by improving performance in parts of the game where you would have dropped rather low
unless your running 4k then you may just be completely gpu bottlenecked everywhere

I should have been more specific, I meant approx 4% max increase to minimum framerate moving from 3000MHz to 3600MHz ram.

its not really cpu overhead from sli its just the higher gpu performance is reducing the gpu bottleneck which shifts to cpu bottleneck

My point was:
SLI needs extra CPU. This doesnt help when already CPU bound with single GPU.
In some situs SLI can reduce performance or reduce smoothness.

ah ok i will fix the links
working now with ?attredirects=0 removed? it was just a system image and fallout4

Yep fixed. I viewed them directly earlier.

the ram is still not really available in au its about twice the price that it is in the us in the few stores that list it so i imported it and the gtx1070 from newegg

Good decision!

i found the info here very useful for tweaking and the tests great for finding problems with stability
[Official] Skylake, Haswell-E & Broadwell-E 24/7 DDR4 Memory Stability thread

I had a read but my PCs security absolutely hates Overclock.net lol.
I didnt see links at the start to anything for Z170 stuff, it must all be contained in the thread.

I just came across this which might be right up your street, although I'm not sure what chips your ram uses.
ULTIMATE B DIE TWEAKING GUIDE FOR ASUS ROG MAXIMUS VIII SERIES - HWBOT forum

I'm interested to see what effect the MAGIC SETTINGS/BOOTING SETTINGS have, but what a pita to set up.
Its nice he gives sample values to try but theres no mention of the effects.
I havent got much time atm to test further.


I tried setting vtt a bit higher but it didnt seem to help. I'll try a bit harder later.
Mine was originally 0.69375V. Your setting of 1.2V is very high! Are you sure thats safe?

ps how do you set tRC?
I cant find it anywhere in the bios.

 

[dasa]

vtt=vccio on the new asus mb (sorry old habit) if yours is that low maybe your looking at something different or your mb handles it different dont know but the color of the number is a good guideline to whats safe when does it go to yellow\pink\red?
mine defaulted to a fairly high level with xmp i have just been keeping it .05v below vccsa which is in the yellow

like yours the reported v in bios for sa\io is higher than what is set in bios\uefi another old habit
vdimm on the other hand undervolts and 1.256v set reports 1.408v
i think i can probably drop them a bit from what there currently at i just had them up to find what was stable then meant to go back later and try lower them but games got in the way

yes i have read that guide it did have some useful info since i have the same memory chips and a similar mb but due to them running massive v with c12 timings that would kill the system quick if used 24\7 a lot of it isnt much value

the oc.net thread shows some good ram tests and a list of systems with there results in the first post
you need to click SKL DDR4 8-16G

 

[Nenu]

Cheers

I have VCCIO and then another vtt is in one of the memory timing sub menu. I've left that alone.
Yeah your VCCIO is good

I did a fair bit of reading and had another go at lowering timings, ended up with...
Yesterdays tweaks:
1.395V 3600MHz 17,20,20,41 tRFC=460
New tweaks:
1.400V 3600MHz 17,18,18,41 tRFC=360

The .005V increase was actually necessary to change the timings from 20 to 18.
I tried using the Asus auto configs for my particular ram chips (old Samsung 4x4GB) but it regularly refused to post even after changing all the settings back to default.
I saved my bios config before trying them out so it was simple to get back where I was.
I also tried the setup for 3766MHz and 4000MHz ram but it didnt help.

Quite pleased with the result so far
I'll have a go at other timings and reading more of that thread when I have chance.

We have practically the same motherboard.
Mine is Hero, the ATX version of the Gene.
Yours is theoretically a bit better at ram clocks due to mATX having shorter trace lengths.