EZ i9 7900X overclocking guide?

[FaaR]

I'm not looking to squeeze every ounce of juice out of this thing; I just want to reap the low-hanging fruit. For one thing, I'm air cooling, so there's not too much thermal headroom before I start hitting wacko temperatures - unless I was to also engage in undervolting, but that's generally counterintuitive when overclocking, so I'm not sure how well that would fly...

What I'd like to do if possible, is say, bump the various base and turbo mode clocks a few bins up. Not lock all cores, but follow the same turbo principle as stock settings. From what I understand, the 7900X is 3300MHz base, 3500MHz AVX turbo, 4000MHz non-AVX turbo 2.0, 4300MHz 4-core turbo 3.0 and 4500MHz 2-core turbo 3.0.

If I could raise all of those say, 200MHz across the board without increasing heat load too much, that'd be nice. Maybe raise the highest turbos 300MHz perhaps, that'd be nicer still. I'd like to also bump cache clock as well, as I've seen people say pretty huge gains can be had from doing that (both CPU performance as well as RAM bandwidth), but I'm unsure how to accomplish that.

I'm at 82-83C package temp right now with a dual-fan Noctua NH-14S mounted to this thing, running Folding@Home on 18 threads - GPU folding reserved for the two remaining threads, but pausing those. (Enabling GPU folding also and dumping heat from 2x R9 390X into case bumps CPU package temp to 86C.) Running Prime95 max burn stress test gives 88C package temp.

I'm on an ASUS Strix X299-XE motherboard, but I figure all ASUS X299 boards use the same UEFI so it probably doesn't matter.

RAM: 8x 8GB G.Skill TridentZ RGB 64GB 3600 16:16:16:36 2T (Enabling XMP profile is the only performance setting I've changed from stock so far.)

(People have asked me, why do you need this thing? Answer is, I don't! This, beeing a life-long geek and a nerd, is my answer to another man's midlife red sportscar. lol)

Any help and other useful input greatly appreciated! Overclocking CPUs is such a science these days, so many knobs and dials to tweak... Geesh!

 

[aigomorla]

ok i hate to sound like a pessimist but a +200mhz overclock will not be worth the losses you will see in power saving features.

So in a nutshell, to get a +200mhz clock on all your cores, you would lose the ability of the cpu shutting down unneeded cores and downclocking for power saving features.

Its like having your engine run @ 100% instead of idling.

So if your wants is that low... i would honestly not recommend it and let it run at base.

Now if you were going after a 700mhz across all core overclock, that would be a completely different story, however as you noticed, you quickly run into the issue of heat because some genius at intel decided we no longer needed a metal solder as TIM.

 

[FaaR]

Why would I lose dynamic clocking and power saving just because I want to change the all-core turbo multiplier from 40 to 42...? From what I understand, none of the turbo modes are hardcoded into the CPU, but rather entirely controlled through software/the UEFI. That's certainly the way it works with Haswell, my old chip. I can change/raise multiplier per core, or on all cores at once, but still retain dynamic clocking and idling.

I bumped my old 4770k from its stock setting of 38 multiplier on 1 core to 40 on all cores, it still downclocks. Has this behavior actually changed in the intervening years...?

 

[Timmah!]

Why would I lose dynamic clocking and power saving just because I want to change the all-core turbo multiplier from 40 to 42...? From what I understand, none of the turbo modes are hardcoded into the CPU, but rather entirely controlled through software/the UEFI. That's certainly the way it works with Haswell, my old chip. I can change/raise multiplier per core, or on all cores at once, but still retain dynamic clocking and idling.

I bumped my old 4770k from its stock setting of 38 multiplier on 1 core to 40 on all cores, it still downclocks. Has this behavior actually changed in the intervening years...?

Nope, you dont need to lose downclocking when overclocking. The whole thing is bit more complex though, with all the dynamic voltage offsets and C-states, its not just as simple as saying if clocks are down, so are the power levels. At least from what i could gather, i am not master OCer.

BTW, 4300 MHz is 2core turbo 2.0, not 4-core.

Per this video, it seems with air cooling 4,3GHz all core overclock is still doable within acceptable limits, i mean temps not going into 90s. Additionally, i saw people with 7900x claiming 4,3GHz is doable on stock vcore (1,1V) - which is good news, if true.

 

[FaaR]

The whole thing is bit more complex though, with all the dynamic voltage offsets and C-states, its not just as simple as saying if clocks are down, so are the power levels.

Yeah! That's my problem; I can't find any good guides or explanations of all these special settings, or really any decent guide at all, even one just going through the basics step by step in a cohesive, accurate way. What I've seen is either like the video you linked to; doesn't explain ANYthing, just waffles on and on in a mumbling, muffled, droning voice with heavy accent until it ends, or it's confusingly written, poorly explained and not even particularly in-depth either...

It was so much easier in the past, but today's CPUs have massive amounts of settings exposed in UEFI, and ASUS' own text hints is often just a repeat of the name of the setting, or something like "set higher if overclocking", but no effort spent explaining why, or even how much higher, or if setting too high could be bad or even dangerous, and so on.

Per this video, it seems with air cooling 4,3GHz all core overclock is still doable within acceptable limits, i mean temps not going into 90s.

That'd be cool, if I could pull something like that off but I'm unsure how voltage offsets and all that works, especially as there's apparently static and dynamic voltage offsets, with the latter also being different for idle and turbo states...? Sheesh, lol. In my day, you hardwired CPU volts with a set of jumper blocks on the mobo and that was that!

Do you know what are considered safe reasonable voltages - especially for air cooling on 7900X? What about AVX mode? How high can one usually push that, again without bumping volts to more than a marginal degree (because CPU's running even hotter doing AVX calculations than regular floating point work...)

Thanks in advance for any assistance.

 

[Timmah!]

While this is a nice message board, the better place to get answers to your questions is Overclock.net

I would love to help you, but as i said, i am not seasoned OCer myself and dont understand all the nuances myself, so i dont want to mislead you. All my experience with OCing comes from playing with 2 CPUs, my current Broadwell-E sixcore chip and previous i7 980x. In both cases, just mild overclocks, i guess something along the line you wish to do. I wanted to go higher with my current chip, but it seemed to require more volts to be stable than i was willing to risk, so i remained satisfied with less. Maybe it was attainable with some OCing mumbo-jumbo, but thats where i was coming short with my knowledge and i did not want to meddle with stuff in BIOS i did not understand properly its inner workings.

Regarding 7900x, i have no personal experience, however i actually own Skylake-X chip myself, the 7940x, since yesterday, but its still in the box. I will deal with it next week. My aim is similar to yours, mild OC on all cores to 4,4GHz, if possible, with no more than 1,12-1,13 vcore applied. I have AiO watercooling set, but its only 240mm Corsair H105, so i have to be sensible and if i wont be able to get stability and satisfying temps at those clocks and volts, once again i will go for less. Even 4,0 all-core instead of stock 3,8 would be nice, you understand :-D Since i have no experience with voltage offsets, i guess i am just gonna set the vcore to static value - this is probably what Aigo is talking about with running your engine at 100 percent even at idle. When you do this, the CPU will still downclock at idle, but even then they will be fed with constant voltage you set in BIOS, at least thats what CPU-Z will report. To my understanding though, the power-saving will still be effect, as that is governed by those C-states, which apparently cuts off all the power to the cores not at use - this is however the part i am not sure about completely and would require further explanation...so take this with a grain of salt, i could be all wrong.

I guess if i were you, i would follow the same steps as i intend to do myself and see where it goes stability and temp-wise. I dont think there is any risk involved - at least i hope so as i would hate to kill that 7940x myself and 1100 EUROs would go down the drain.

 

[aigomorla]

Why would I lose dynamic clocking and power saving just because I want to change the all-core turbo multiplier from 40 to 42...? From what I understand, none of the turbo modes are hardcoded into the CPU, but rather entirely controlled through software/the UEFI. That's certainly the way it works with Haswell, my old chip. I can change/raise multiplier per core, or on all cores at once, but still retain dynamic clocking and idling.

I bumped my old 4770k from its stock setting of 38 multiplier on 1 core to 40 on all cores, it still downclocks. Has this behavior actually changed in the intervening years...?

let me explain it on why...

Dynamic overclocking has to do with multiplier settings and voltage set via bios.

So if you overclock and play with voltage, then when the cpu does downclock, the voltage downclocks in scale with the multiplier.
This can then lead to the cpu being unstable at the downclock settings if you also messed withe memory and other settings.

This is why the first thing one typically does when overclock is disable all the power saving features of the said cpu, otherwise you have a chance of the system not being stable.

The higher the overclock with more fine tuning, the more chances of it not being stable when it goes into power saving mode because the settings which the base defines as stable is no longer applicable due to the overclock.

Also unless its been changed, the moment you change stuff from default to a set value, i believe you lose dynamic overclocking, or bios will automatically disable it on ASUS boards. This is because ASUS knows you want stability more then dynamic overclocking. Well on my RoG class boards this always applied.

Again i havent had a chance to play with the 7900X because i am still waiting for the 7940X, however on my 7740X when i clocked it to like 5.3ghz, i havent seen it once downclock or use dynamic overclocking so i assume the same rules will apply.

 

[FaaR]

While this is a nice message board, the better place to get answers to your questions is Overclock.net

Haha, thankses! I didn't know about this website, I assumed that Anandtech, being such a long-existing hardware website, was an ideal place to ask about this stuff. I sincerely appreciate the input and help you've offered.

Anyway, enjoy your new toy... I wish you much success!

 

[TahoeDust]

ok i hate to sound like a pessimist but a +200mhz overclock will not be worth the losses you will see in power saving features.

So in a nutshell, to get a +200mhz clock on all your cores, you would lose the ability of the cpu shutting down unneeded cores and downclocking for power saving features.

Its like having your engine run @ 100% instead of idling.

Sorry man, this isn't true. I am running my 7820x at 4.8GHz. it still down clocks and steps just like a normal CPU. All power features are there. Right now it is idling at 1200MHz, 23c, using ~65w.

OP, I have a Gigabyte board, but I am sure Asus has a setting similar to the one shown below. If I understand what you are wanting to do, this is where you would set it up. Look at the stock setting and decide how much you want to turn up each core usage scenario.

You will probably have to add some voltage offset. Watch temps, and adjust AVX and AVX 512 ratios as needed to keep things cooler under those loads.


And yes, the intel CPU section of overclock.net is where you want to be for real overclocking knowledge.

 

[Timmah!]

Haha, thankses! I didn't know about this website, I assumed that Anandtech, being such a long-existing hardware website, was an ideal place to ask about this stuff. I sincerely appreciate the input and help you've offered.

Anyway, enjoy your new toy... I wish you much success!

You are welcome. Regarding the Overclock.net, what i meant, it has higher traffic than these boards, so bigger chance IMO to get any answer. Although, as you can see, there are people willing to help over here as well, and by that i dont mean now just me or Aigomorla.

Wish you success in your OCing endeavours as well!

 

[FaaR]

Right now it is idling at 1200MHz, 23c, using ~65w.

Is there a way to set a lower idle multiplier? As I recall, my haswell can idle down to like, 150MHz or maybe even lower, I'm not sure. 1200 seems kinda overkill for idle clock.

If I understand what you are wanting to do, this is where you would set it up.

Yes, this is exactly what I'd like to do, thank you.

You will probably have to add some voltage offset.

The trick would be to add volts only at top clocks, not idle... I believe there's a way to do this, but as I've never tried it's uncharted territory for me (with a very pricy CPU at stake, heh.) As for how much extra (milli)volts would be appropriate I have no idea.

Watch temps, and adjust AVX and AVX 512 ratios as needed to keep things cooler under those loads.

What is a good AVX and AVX512 diagnostic tool to use for such stress testing? Prime95 uses AVX from what I know, but I don't know if it supports AVX512 as well, or how I'd switch between the two...

Made an account at overclock.net, we'll see if I get a response there. Thanks for your help so far, it's much appreciated!