4790k OC final stages - please help with suggestions to find stability (using uncore, VRIN and RING BUS voltage tweaks)

[MGediG]

SPECS:

4790k
Noctua DH15S

5 other fans including industrial top fan
Gigabyte z97mx Gaming 5
16gb Ballistix Tactical (OC to 2133 with 10 9 10 24 CR1 and ram enhancement set to "stability" in BIOS, 1.52 Volts)

Fractal Define Mini Case
EVO SSD

Aim is to achieve 4.9 Ghz stable on lowest voltages possible, the thing I'm confused about is the voltage leap from 4.8 - 4.9 and the general instability I'm getting as I tweak the overclock around 4.9 relative to the stability I have found at 4.8.

I know things like uncore, VRIN and RING BUS tweaks can all aid the stability and temperatures of the overall overclock. I've lost an old link that explained a lot of this, so hoping the community can chime in.



I've been overclocking my 4790k for some time at a few different speeds between 4.7 and 4.9Ghz. The last stable long term overclock I had I left it on 4.7 at around or a bit below 1.26Vcore I believe.

For some reason all my BIOS settings reset at some point, I honestly can't remember why, when or how this might have happened. The point being that I don't know what my old settings were, and no matter.

Now but I'm trying a new approach to squeeze better single threaded performance for some flight sims I'm playing (il-2 sturmovik series, BoX and CloD).

I have achieved good results so far, please note I have hyper threading off, all c states off, turbo off and power management to performance in Windows.


This overclock is passing the stress tests (p95, AIDA64), but temps going a little high for my liking at this stage (peaks 85).. I don't mind high temps in stress test but hoping for under 80. Also I'm getting crashes while gaming, after 30-60 mins. Possibly could be related to GPU but not so likely IMO.

49 core multiplier
40 uncore

Vcore 1.356
VRIN 1.78
RING BUS 1.151


This overclock is perfectly stable, and as you can see it's much lower voltages, and I'm getting temps peaking at 75 in stress test, which is great as far as I'm concerned.

48x
40uc

Vcore 1.28
VRIN 1.71
RING BUS 1.14

I'm tweaking it lower and lower, but the other OC seems to be going higher and higher...

Can anyone suggest what might be my bottleneck for stability and temperatures?

Why is the leap so big for the Vcore from 4.8-4.9? I expect I should be able to get a much lower Vcore for 4.9 if I can find the right settings for the other variables...

I guess I can try to drop the uncore to about 35ish for some tests, and also drop ring bus along with that, so that should take some stress out of the system, though I wanted to keep uncore around 40 in an ideal world. I'm not quite sure how to judge dropping the ring but relative to everything else though... how low can it go?

NB - I don't mind hitting slightly above 1.3 Vcore, and I don't mind hitting 80C in stress tests, as they are unnatural and not representative of what I'm doing every day. I only need another year out of this chip...

thanks for reading!

 

[MGediG]

What I'm thinking now is I'd like to overclock the single core above the others, but I'm not really sure how to do this.

I saw here http://edgeup.asus.com/2014/6-4970k-cpus-overclocked-oc-impressions-of-devils-canyon-on-asus-z97-motherboards/ that it's possible, but not necessarily on my board...

So I've been trying to play with turbo, and the aim would be for turbo single core 51, double core 50, and for the 3 or 4 cores at 48 (which is where I'm stable at the moment).

Everything seems pretty good and stable, some benchmarks are better, some are the same, until I do a couple of more intensive benchmarks specifically for single thread, and the temps go through the roof. I think "auto" for watt and amp management for turbo is causing some problems here, and I don't know how to tweak that either...

It may also be that I can drop the 2 core turbo to 49 for a safer "transition".


Also I'm not totally sure on how games/apps handle swapping between single/multi core usage, but I assume it's happening all the time - so there will be times when single core turbo is useful during game playing etc. Benchmarks seemed to show this, as they were not totally single core dependent benchmarks but I still got better scores with these changes.


Do I need to go to a more hardcore overclockers forum for this stuff?




EDIT: so something has changed since I tried the turbo OC idea - I now can't get stable 4.8 below 1.286Vcore... Possibly because I'm impatient and my idea of stable is 20mins + small ffts and about the same of aida64, and today is a hot day. But I wonder if I jarred the cpu a bit with the attempt at 51x for turbo without managing the power.

I will probably be trying to stick at 48 now, but I would really like to overclock the single core.