6700k Overclock questions.

I have a I7 6700k Revision R0 cpu in a MSI z170Z Gaming M7 mobo.
For a log time I left my OC very mild at 4.2 GHz, but decided I wanted to push it up to 4.5 GHz, I am air cooled, but I have a HAF 922 case, lots of extra fans, and a Cooler Master evo 212 cpu cooler with a second fan added to get that push/pull config.
At 4.5 GHz my cpu seems stable so far, still need to do some more testing, but I noticed something, my NB frequency is only at 4000 MHz, I did not mess with it at all, is that going to cause any bottlenecking?
If so, then how can I raise it safely to match the cpu frequency?

My RAM is DDR4 3000, I am running it at 1500 MHz which would be my XMP profile. Timings are 15-17-17-35 at 2T Voltage stock at 1.325V
https://www.newegg.com/Product/Product.aspx?Item=N82E16820233863

My cpu voltage is set to 1.35v, but cpu-z shows 1.328v.
During a little stress testing I seen the Vcore go no higher than 1.336v, temps got no higher than 70c at 100% cpu stress testing.

I am not new at overlclocking, but to be honest I am fairly new to overclocking the newer cpu's, I have a lot of time invested in learning to overclock older cpu's like the Q9550, and a few others.
I have speedstep and all disabled, I know with previous cpu's those could cause instabilities, I am assuming that still remains true?

Hopefully some of you have some helpful tips, and can answer my question about the cpu-nb frequencies not matching.
If there's any other info needed let me know and I'll post it up.
NOTE: I watched several videos and read several threads on OC'n this cpu on this mobo, but none really shed any light on my cpu-nb frequency question.

Thanks for any help ahead of time.

Well on the newer chipsets the NB is integral to the cpu. Depending on the mobo it will be referred to differently such as ring/cache/uncore/etc. I believe in the msi board you will be looking for Ring ratio. On the 6700k the ring and core share the same voltage rail so your vcore will directly effect the ring ratio overclockability. I try to keep the ring within 400 mhz of the core. Unless you are benchmarking or running certain programs you will not see a huge gain by running a 1:1 ratio of the core to ring.

As for the voltage not matching this probably had to do with the LLC setting of the mobo.


As for the speedstep, it has gotten better in recent years. On my 24/7 rig I turned it off to test my overclock and then turned it back on when I found a happy medium.

At that voltage I would expect you have a little more in that chip but cannot say that for certain.

I'm not familiar with what chip is in that memory but you should be able to do 3600 16-16-16-36 2t or 17-18-18-38 2t pretty easily.

Ahh ok, I seen both ring and cache in the mobo settings, I'll see if I can get it closer to 1:1, I remember trying to get a 1:1 ratio on the older chips, and while it was a bit easier I never really pushed for 1:1 because I tried to OC both CPU and then RAM as much as possible, which rarely resulted in a 1:1
Right now I am at a 1:30 FSB to DRAM ratio, lol

I went ahead and enabled EIST and tried a quick stress test, as well as let it idle for a while, and it did not cause any instabilities, which is good because I only want to push it if I am gaming, or doing something like video/audio rendering.
If my CPU is at 4500 Mhz and the NB is at 4000 Mhz then there is only a 500 MHz difference, still I'll see if I can figure out how to up it like 100-200 MHz.
I really don't want to push the RAM unless I have to, because when overclocking any instabilities I have encountered are usually from the RAM, I do want to get a little more out of it if possible though.
I read where some mentioned getting 3100 and up on stock, so I may be able to get a bit higher than the XMP 3000 MHz.
I'd get some newer faster DDR4, like some rated at 3600 MHz via XMP, but I could not find any with a low profile, and I don't think a full size RAM stick will fit, I have very little clearance from the cpu heatsinks fan..

Thanks for the help.

Don't disable Speed Step. Your CPU will unnecessarily run at full speed all the time. It does not seem to create instability in the newer Intel products.

Leaving the cache at stock while overclocking the cores will cost you little if any performance loss. It would show up in benchmarks but have little or no impact in real world computing. And you will have trouble getting the cache to run 1:1 with the cores beyond a very mild overclock. And it will need more voltage to get the same amount of overclock, generate more heat and generally hamper the much more important goal of getting the best possible overclock on the cores which is where the performance is.

CPU voltage in CPU-z is showing lower than what it is set to in bios because of vdrop. It's normal. You can compensate for that with adjusting LLC which may be in the "Digi VRM" section of overclock variables.

EIST is going to stay enabled, I upped my RAM to 3200 to get a 1:24 ratio, but I am not sure how much more I can push it, I had to loosen timings from 15-17-17-35 to 16-19-19-38, I may try to shoot for 3400 at the same timings if possible, but I am not sure if this RAM can handle it or not, some said in the comments on newegg that it did not OC well in the Z170 mobo's, hopefully they were wrong.

So far I am happy at 4.5 GHz, I raised the multiplier to 45, I did not mess with the base clock.
I am just still wondering is it is much to gain by raising the NB clock any, I found it labeled as ring, and it is set to auto, but I can input a manual number, what I found weird is it actually showed it as 4100 MHz under Auto, when it only shows as 4000 MHz under CPU-Z.
I understand vdrop a bit, hopefully the .22v drop is not too bad, the voltage does fluctuate a bit though, HWMon shows it go from a min of 1.304 v to 1.336 v.
When stressing the CPU at 100% it seems to say at 1.328 v, which is not too bad, at 100% I am now seeing 70-73C max, I am good with that, and really don't want to go higher with the cpu overclock.
I just want to see what I can squeeze out of the RAM, and if it would be worth it to up the ring to say 4100 or 4200, if that gain is really negligible then I am fine with leaving it at 4000.

One thing I found weird is the RAM was bought as DDR4 3000, but I see under SPD on CPU-Z that each stick of RAM says under Max Bandwidth DDR4-2133 (1066 MHz), not quite sure why it lists as that...

Thanks for the response.

Tried the RAM at 3600 MHz at stock 1.350v and it would not boot into Windows, had to raise it to 1.400v, I cannot drop the timings and keep it stable, it seems now I have a 1:27 ratio, and timings are 18-21-21-42, I see some 3600 MHz sticks are rated at 17-18-18-36, so I guess this is not too bad, I am not sure I like upping the voltage so much, I may bump it down a tad and see if it will still boot. Maybe try 1.375v
If all else fails I'll just drop back to 3200 MHz, I am fine at that till I can get some better RAM.

Overclocking the memory will add complexity to the overclock but yield almost "0" performance improvement. For the vast majority of applications, high speed memory is a zilch as far as performance improvement is concerned. Some games benefit a little I'm told.

I was mistaken when I put 1.35v for the cpu voltage, I actually put it at 1.325. which makes a lot more sense, as that was a lot of vdrop before, lol my mistake.
I cannot boot with the RAM at 3600 MHz unless the voltage is at 1.400, I tried to go from 1.360 to 1.370 to 1.380, and 1.390, none would let Windows boot.
Not sure if it is stable yet though, I have my doubts since it was failing to boot at just .010v less..

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Very good point trents, I am sacrificing timing for frequency anyway, I am sure I'd get more life out of the RAM at 3200 MHz, it will run at that on stock voltage.
I just wanted to see how far I could push it.

Jar said:

I was mistaken when I put 1.35v for the cpu voltage, I actually put it at 1.325. which makes a lot more sense, as that was a lot of vdrop before, lol my mistake.
I cannot boot with the RAM at 3600 MHz unless the voltage is at 1.400, I tried to go from 1.360 to 1.370 to 1.380, and 1.390, none would let Windows boot.
Not sure if it is stable yet though, I have my doubts since it was failing to boot at just .010v less..

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Very good point trents, I am sacrificing timing for frequency anyway, I am sure I'd get more life out of the RAM at 3200 MHz, it will run at that on stock voltage.
I just wanted to see how far I could push it.

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Understand. I do things like that too. It's the challenge. Make sure you do some thorough stress testing. Running the RAM at that speed may or may not suggest adding a little voltage to the system agent to give a little more push to the memory controller. It isn't rated for that frequency of RAM but may cover it anyway without more voltage.

Yeah I will stress test it for a while, did a little gaming and so far so good, but I know that does not mean it is stable.
The mobo I have says it can handle up to 3600 MHz RAM if OC'd.
https://www.newegg.com/Product/Product.aspx?Item=N82E16813130872

If it does not pass stress testing I'll try bumping up the voltage by .010v and see if stable then, if not I am willing to go .010v higher, but if it takes more than 1.370 I think I'll just drop back to 3000 MHz at 1.350 and wait till I can get better RAM.

Better RAM? Is there something wrong with what you are using now?

No my current RAM is fine, I meant RAM rated to run at a bit faster speed, that way I can possibly hit 3600 MHz, and be at the fastest speed my mobo is said to run.
I would just stick with the 3000 MHz, but I planned to help my brother upgrade his rig, so I figured I'd get the 3600 and give him my 3000...

What does the Vccsa and Vccio show in HWiNFO64 With XMP?

Jar said:

No my current RAM is fine, I meant RAM rated to run at a bit faster speed, that way I can possibly hit 3600 MHz, and be at the fastest speed my mobo is said to run.
I would just stick with the 3000 MHz, but I planned to help my brother upgrade his rig, so I figured I'd get the 3600 and give him my 3000...

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Okay but you won't see any performance increase. If you just want to do it to help your brother and to support the tech industry with more of your dollars go ahead.