Seeking Help w/Finding Right Performance-Temp Balance for New i7-8700k Build

[MrELB]

Hi and thanks for reading.

 

I'll start by saying that I have very little OC knowledge and experience. As the saying goes, "Just enough to be dangerous." 

 

To get it out of the way, here are my specs:

• CPU: i7-8700K w/CoolerMaster Hyper 212+ heatsink
• RAM: 16 GB Patriot Viper DDR4-3400 
• Mobo: ASRock Z370 Extreme4 
• GPU: Zotac Amp! Extreme Core GTX 1080Ti (boosting to 1999 MHz)
• Case: Phanteks Enthoo Pro w/five fans (1x200mm front intake, 1x140mm bottom intake, 1x140mm rear exhaust, 2x120mm top exhaust)

Last night I reconfigured my fans some to improve monitoring. Once that was done the system seemed to be running pretty cool — CPU was 25-35 C idle and 40-50 C in games (with brief spikes to 65 or so); GPU was boosting to 1999 MHz @ 50 C in games. 

 

But I wanted to get a little extra from my CPU and RAM. What I had my sights set on was getting all CPU cores to run or boost to 4.7 and to up the RAM, which is DDR4-3400, to go from the mobo's default setting of 2133 MHz to 3200 MHz. Several folks have informed me that 3200 MHz is the sweet spot, while going to 3400 MHz could be trickier (I'll admit that I don't fully understand why...timings? voltage?).

 

Problem is, outside of enabling the XMP profile, which is easy enough, I don't understand how to OC my RAM (i.e., what settings need to be adjusted) or what to set it to in the ASRock Z370 bios. So, I first enabled the only XMP profile the RAM came with, which is for 3400. Then I also set the CPU OC target to 4.7 via one of the easy OC settings in bios. Because of the changes already in place to take the RAM to 3400, this translated to a jump to about 4.8 on the CPU. I figured that wasn't much higher than my goal, and not unrealistic for the 8700k, so I went with it.   

 

It ran fine and temps in game were good all around (generally 45-55 C w/brief spikes to maybe high 70s). But then I tested the CPU with Prime95's "balanced" test. At first, the CPU held down the temps pretty well, but about five or so minutes in the temps shot higher and I hit 100 C on one of the cores momentarily and stopped the test at six minutes.

 

I know Coffee Lake runs hot, and I'm air cooling a non-delidded processor. But still hoping that I can get the 4.7 (all cores) and 3200 RAM speed I'm aiming for without risking the CPU. 

 

Any guidance, input, insights and straight-up bios-setting instructions would be greatly appreciated. Thanks for your time.

[SneerRolts]

I would point you over to my thread/post: 

 

Your default bios settings are pumping to much voltage causing it to heat up drastically. That said if you got your temps to 80C then you would be fine. I am air cooled but with a beefier heatsink.

 

Core ratio which is 49 means 4.9GHz speed.. so just lower it to 47 for 4.7GHz

 

I havent done any RAM OC so cant comment on that part.

[MrELB]

2 hours ago, SneerRolts said:

I would point you over to my thread/post: 

 

Your default bios settings are pumping to much voltage causing it to heat up drastically. That said if you got your temps to 80C then you would be fine. I am air cooled but with a beefier heatsink.

 

Core ratio which is 49 means 4.9GHz speed.. so just lower it to 47 for 4.7GHz

 

I havent done any RAM OC so cant comment on that part.

I read the thread link you sent, thank you. Some of it is over my head at this point and I plan to read it again. What I do understand is that your voltages are "throttling down" when CPU load is less, saving power and heat during those periods. What I'm not clear on is whether this is also lowering your temps under load, say, when playing a CPU-intensive game. Are your temps lower in these instances as well?

 

Further, I just need to understand OC'ing and all the involved variables better in general. For example, I don't know what Load Line Calibration (LLC) actually does. 

 

Finally, I'm not sure what you meant when you wrote: "You should know via testing in Manual mode to find out the stable OC voltage that works for your CPU. So if it was pushing 1.28v and you want 1.32v then you would want an offset voltageof 0.04." This line seems pretty critical, but you wrote that your stress tests "pushed 1.28v" but "you want 1.32v," so set an offset of 0.04. If stress tests demanded 1.28v, why wouldn't you want 1.28v...why set it at 1.32v? To have extra?

 

Don't mean to be challenging, but trying to figure out the value of this for my situation. Thanks!

[SneerRolts]

Ooops I may have complicated matters for the sake of your purposes for now.

 

You would need to do a manual overclock at first to find out the best voltage/speed for your cooling setup. If you know nothing about overclocking I would recommend watching this video: 

On other motherboard brands some of the options will be in different headings/menus but it will give you a good general idea. That video should give you a very good idea how to set a voltage then stress test then adjust as needed (or repeat until success is had). 

You would need to put it to go up to 4.7GHz, then play around with the voltage to find out the sweet spot. You always want to stress test to find out if it works. If it is working then go down until it stops working then one up and stress test for a longer test. If it passes great, if it fails go up one more notch and repeat. Once you know what voltage and speed leave you with a temperature on your CPU that wont mean it will die young, then you mess about with adaptive overclocks. Overclock the CPU first, then do the RAM afterwards just to avoid any other issues. The CPU clock is whats going to make a much performance increase overall.

 

8700K cpus run hot because the motherboards pump more power into them than they need by default. Reason being they are set to send the highest amount of voltage for a badly binned CPU to get a successful overclock, rather than the average or your one if you have the chosen CPU foretold by the gods upon one summers night. The lower voltage being fed to your CPU for it to do its job properly the less hot it will run.

 

Worst case scenario if your cooler is the limiting factor and you don't want water-cooling then the best air cooler (which I use) is noctua nh-d15. So getting a maximum of 78C at load after 3 hours is possible on air, probably better with an case that allowed a bit more airflow than mine... that's with mine OC'd to 4.9GHz. 

Make sense? I could have massively oversimplified it for you (as I don't know your knowledge level) or been unclear.

 

P.S. If no matter what you do, you cant get it run much cooler, it could just be a really really really bad cpu. Luck of the draw and that.

[Clarhett]

To O.C or not to O.C, cpu or your memory. Well both can be tricky and confusing, the easier of the two (2) to do is over clocking the cpu, and on an Asrock motherboard you have many advantages in the bios to allow you to tweak the cpu and the memory for that matter. As far as getting temps down on your cpu, if you are planning on not de-lidding the cpu, then you might have to try alternate ways of cooling via air-cooled heat sink and fans attached to that heat sink, or switch to a water cooled closed loop AIO pump and rad - like a Corsair H90 (140 mm rad and 140mm fan) As far as figuring out memory timing I suggest you take a peek at these two videos. Yes they are complicated, but if you can follow along it will be worth the effort. 

 

 

 

[MrELB]

Well, I just OC'd my CPU really for the first time, and here's where I landed:

• The below is with all fans on max.
• I tried 4.8 GHz at 1.216v and got errors in Prime95 26.6 "blended" and, ultimately, BSOD
• I tried 4.8 GHz at 1.232v and got 1 error in several tests in Prime95 26.6
• I tried 4.7 GHz at 1.232v and received no errors in Prime95 26.6 over about a 20-minute period
• I ran Prime95 26.6's small FTT heat torture test and the CPU went to 99 C
• I ran Cinebench about 10x and it got up to 89 C
• During the blended Prime95 tests my temps were mostly around 60 C, but one core did reach 91 C at some point
• My idle temps are about 32 C avg
• I did OC my RAM to 3400 at (16-18-18-36) 1.35v and ran Prime95 again with no errors (after about 15 mins)

So, what's next? Feels like I definitely shouldn't go any higher in voltage, though I'm not sure whether I'm likely to see anything like the stress that Prime95 can throw at the CPU in normal and gaming usage. Are there any other tweaks, beyond buying a new cooler, to make the system run cooler (any other voltages to experiment with)?

 

I'd also like to tune the CPU voltage as an offset rather than a fixed amount. But I'm not sure how to turn the 1.232 fixed number I arrived at above into an offset. I'm also thinking that I should put a 300 MHz decrease in for AVX tasks, since that seems to stress the CPU the most.

 

Anything else — bios settings, etc. — you'd recommend?

[DarkSmith2]

24 minutes ago, MrELB said:

I'd also like to tune the CPU voltage as an offset rather than a fixed amount. But I'm not sure how to turn the 1.232 fixed number I arrived at above into an offset. I'm also thinking that I should put a 300 MHz decrease in for AVX tasks, since that seems to stress the CPU the most.

why would you want that? It just makes things more unpredictable and unstable to use offset voltage for negligible power savings. like saving 4watts...

 

21 minutes ago, MrELB said:

So, what's next? Feels like I definitely shouldn't go any higher in voltage, though I'm not sure whether I'm likely to see anything like the stress that Prime95 can throw at the CPU in normal and gaming usage. Are there any other tweaks, beyond buying a new cooler, to make the system run cooler (any other voltages to experiment with)?

If you really want to get more out of your cooler you are kinda forced to delid your CPU.

[danrey84]

First off all 8700k when overclocking is a known for being hot. While I'm not saying your chosen cooler is a bad 1 when it comes too overclocking you really need a high quality air cooler for example noctua or some form off AIO. The LLC settings are all about getting the right balance cause as the CPU is under full load the LLC settings dictate what voltage is being fed. More voltage equals more heat which in turn can force throttling not just from the CPU but also from the VRM's. 

[MrELB]

Assu

22 minutes ago, DarkSmith2 said:

why would you want that? It just makes things more unpredictable and unstable to use offset voltage for negligible power savings. like saving 4watts...

 

If you really want to get more out of your cooler you are kinda forced to delid your CPU.

 

4 minutes ago, danrey84 said:

First off all 8700k when overclocking is a known for being hot. While I'm not saying your chosen cooler is a bad 1 when it comes too overclocking you really need a high quality air cooler for example noctua or some form off AIO. The LLC settings are all about getting the right balance cause as the CPU is under full load the LLC settings dictate what voltage is being fed. More voltage equals more heat which in turn can force throttling not just from the CPU but also from the VRM's. 

Assuming I'm going to stick with my current cooler for now (I haven't had a chance to really game with the system yet, so I have no idea if/when I'm going to run into CPU-limited issues vs the far more likely GPU-limited ones), is there anything you'd suggest doing?

 

Does the temp performance in the stress tests I've submitted the build to (around 90 C in Prime95 26.6 and Cinebench at peak) seem acceptable or should I be worried about those numbers? Am I likely to run into games that run the CPU that hot because I feel like I'm right on the limit even though my OC is very tame (4.7 on all cores vs. 4.7 single-core boost). Honestly, in terms of game performance, even the minor OC I've done to 1.232v may not be worth it vs. stock, I suppose (though I haven't yet been able to determine what stock loads are...perhaps 1.20v?).

 

Any further insights would be appreciated, though I'm thinking I'm close to where I want to be given the hardware I'm running. 

[danrey84]

13 hours ago, MrELB said:

Assu

 

Assuming I'm going to stick with my current cooler for now (I haven't had a chance to really game with the system yet, so I have no idea if/when I'm going to run into CPU-limited issues vs the far more likely GPU-limited ones), is there anything you'd suggest doing?

 

Does the temp performance in the stress tests I've submitted the build to (around 90 C in Prime95 26.6 and Cinebench at peak) seem acceptable or should I be worried about those numbers? Am I likely to run into games that run the CPU that hot because I feel like I'm right on the limit even though my OC is very tame (4.7 on all cores vs. 4.7 single-core boost). Honestly, in terms of game performance, even the minor OC I've done to 1.232v may not be worth it vs. stock, I suppose (though I haven't yet been able to determine what stock loads are...perhaps 1.20v?).

 

Any further insights would be appreciated, though I'm thinking I'm close to where I want to be given the hardware I'm running. 

Personally at the moment IMHO I would just run things at stock till you decide what cooler you want to get. As most games even on a stock 8700k you won't have a single problem. Don't get me wrong the 8700k when overclocked is a monster chip and you do get some gains. Thing is when overclocking the goal is to get the most speed with rock solid stability at the lowest voltages possible and it's a VERY fine line and can days if not a few weeks too really tweak.  The problem is with 8700k and it's predecessor the 7700k is they just have TIM which is terrible especially for the price you pay. So your already up against it because the biggest fight straight away are thermals. Hence why alot of people and not even hardcore overclockers delid them and replace the TIM cause they no they can already make there thermals better between 10 and 20 degrees which then means then you tend not to need as much voltage.