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Hello everyone,

I recently made a major upgrade to my PC. My current rig is as follows:

  • GPU: Gigabyte GTX 1080 Ti OC
  • CPU: i7-8700K
  • RAM: G.Skill 2x8 GB 3200 MHz
  • MOBO: AsRock Z370 Extreme4
  • COOLER: Corsair H115i AIO
  • PSU: Seasonic Focus 750W
  • STORAGE: 240 GB SSD for Windows and essential programs, 1 TB SSD for P3D, 1 TB HDD for simple things
  • CASE: Corsair Obsidian Series 750D

Obviously I want to OC the system so I can take full advantage of its power. I did many some test, these are the results:

wjqcFcm.png

 

It is quite disappointing in my opinion. I finally settled for the green row settings - 4,8 GHz, 1,18 V and HT on. However, the P3D keeps crashing (BSOD) approximately 40 minutes into flight. (FSLABS A320 and other demanding add-ons).

When I turn HT OFF, the OC is much better. I'm stable at 5,1 GHz and I can even finish some tests at 5,2 GHz (reasonable temps around 80 °C). But I keep hearing that i7-8700K with HT OFF is essentially a more expensive i5-8600K.

So I'm not sure what to do... My options:

  • Increase voltage to 1,20 @ 4,8 GHz & HT ON (temps in the sheet are lower there, but the test was made on a different day and I have no idea why)
  • HT OFF and OC to 5,1 GHz (is it really like i5-8600K with HT OFF?)
  • Send the CPU for delid

What do you guys think? Do you get similar results with the i7-8700K?

Any advice will be appreciated 🙂 Thanks.

Tomas

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Hi,

What I think:

1. Forget HT with P3D, this is totally useless in this context and brings higher temps, so many problems and more stress for the CPU.

2. I delidded myself my CPU (i7 8700k) and it surely helps containing temperature.

3. Going to 5.1, 5.2 Ghz gives a ridiculous performance improvement (2%?) at the cost of more stress, voltage and heat to the CPU, giving finally a reduced timelife for the chip.

Patrice.

 

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7 minutes ago, patrice_bambou said:

Hi,

What I think:

1. Forget HT with P3D, this is totally useless in this context and brings higher temps, so many problems and more stress for the CPU.

2. I delidded myself my CPU (i7 8700k) and it surely helps containing temperature.

3. Going to 5.1, 5.2 Ghz gives a ridiculous performance improvement (2%?) at the cost of more stress, voltage and heat to the CPU, giving finally a reduced timelife for the chip.

Patrice.

 

Hi, thanks for the reply. So basically you are saying that I should delid and do 5,0 with HT OFF?

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Not nearly enough voltage for that clock. I would say start at more like 1.24v and run prime95 for 30 minutes. If it’s not stable then increase to 1.25v and try again until it is. If your cooling can’t keep temps under 70c at that voltage then you need to buy something else or investigate the thermal compound and contact to the processor and cooler. My 8700k needs 1.285v for 4.9 and 1.365 for 5 ghz. Huge jump for only 100mhz more.  It won’t run at any speed above 5 ghz with HT on. I tried all the way to 1.42v until my cooler couldn’t keep temps below 95. If you are getting BSODs then you aren’t stable and you need more voltage. 

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I'd go with 5.1GHz HT OFF.  In my experience with P3Dv4 on a hexacore CPU, HT off is smoother than with it on, and as you observed, with HT off you can get a >6% clock speed boost over your best HT-enabled overclock.

I don't think delidding is necessary unless you get a real heat monster of a chip.  The extra 100 MHz you might gain, or the 5-10 deg temp drop aren't, IMHO, worth voiding the warranty.  Also, consider running a non-AVX stress test instead, something like Prime95 with the AVX instructions disabled.  AVX presents an unrealistic FP load on the CPU that's not at all typical of P3D, or for that matter most other software. 

The i7-8700K brings 33% more L2 cache (12MB) to the table than the i5-8600K (9MB), so even with HT off, it's something more than just an expensive i5.

Regards

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One more thought w/r/t your temps--make sure you have a good fan curve set up on that H115i.  One of my secondary boxes has a 7700K on an H110i, and the default fan curve is dismal--it does not even begin to keep up with the CPU when it gets loaded up.

I programmed the curve (using the Corsair Link software) to keep the fans at 500 rpm until 25 deg coolant temp, then ramp up to full speed at 30 deg C.  This avoids lots of speed shifting on the fans as the CPU temps fluctuate, and it responds fairly aggressively to actual heat in the system as it is loaded up.  If you're just using the default fan curve, it is not surprising that your temps spike high.

Regards

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2 hours ago, Thomasso said:
  • Increase voltage to 1,20 @ 4,8 GHz & HT ON (temps in the sheet are lower there, but the test was made on a different day and I have no idea why)
  • HT OFF and OC to 5,1 GHz (is it really like i5-8600K with HT OFF?)

Try increasing your temp to 1.350. I did an offset of 0.280 v. and I'm stable at 5.1 Ghz on all cores and never exceeds 70C. 

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Quote

or the 5-10 deg temp drop aren't, IMHO, worth voiding the warranty. 

 

I'm nor agreeing or disagreeing regarding voiding ones warranty... just pointing out that with liquid metal the drop in temp is more like 10 to 20 degrees. 5 - 10 degrees would be delidding with conventional TIM. Nobody should delidd unless they can afford to replace their CPU. Having said that, the practice is a lot safer now with the available delidding tools and reasonable care.

 

 

Edited by martin-w

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8 hours ago, J0nx said:

Not nearly enough voltage for that clock. I would say start at more like 1.24v and run prime95 for 30 minutes. 

 

Theoretical max voltage for the 8700K is 1.5 volts. I'm not recommending that anyone use that voltage, as high temp is the obvious peril, just to give some perspective on why the OP's voltage is relatively low. 

My 8700K does 5 GHz on all cores at something like 1.34 volts I recall. It's delidded. Max it will do is 5.2 GHz at over 1.4 volts. 

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Thanks for all the replies! I'm currently at work, I will write back when I get home. 🙂 

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18 hours ago, J0nx said:

Not nearly enough voltage for that clock. I would say start at more like 1.24v and run prime95 for 30 minutes. If it’s not stable then increase to 1.25v and try again until it is. If your cooling can’t keep temps under 70c at that voltage then you need to buy something else or investigate the thermal compound and contact to the processor and cooler. My 8700k needs 1.285v for 4.9 and 1.365 for 5 ghz. Huge jump for only 100mhz more.  It won’t run at any speed above 5 ghz with HT on. I tried all the way to 1.42v until my cooler couldn’t keep temps below 95. If you are getting BSODs then you aren’t stable and you need more voltage. 

I figured 🙂 The problem is that my CPU starts to overheat above 1.20 V with HT ON. There is just no way around it. I even pumped the H115i on 100 %, both fans and pump. Still massive overheating.

 

18 hours ago, w6kd said:

I'd go with 5.1GHz HT OFF.  In my experience with P3Dv4 on a hexacore CPU, HT off is smoother than with it on, and as you observed, with HT off you can get a >6% clock speed boost over your best HT-enabled overclock.

I don't think delidding is necessary unless you get a real heat monster of a chip.  The extra 100 MHz you might gain, or the 5-10 deg temp drop aren't, IMHO, worth voiding the warranty.  Also, consider running a non-AVX stress test instead, something like Prime95 with the AVX instructions disabled.  AVX presents an unrealistic FP load on the CPU that's not at all typical of P3D, or for that matter most other software. 

The i7-8700K brings 33% more L2 cache (12MB) to the table than the i5-8600K (9MB), so even with HT off, it's something more than just an expensive i5.

Regards

That's actually what I'm trying now. Well, I am at 5.0 GHz @ 1.35 V, HT OFF. Just took off EDDT in the FSLabs A320, everything pretty much maxed out, and so far I got average 53 FPS. That's awesome imho 🙂 One of the cores spiked to 85C once, but normally all of them are below 80. Fan is at 1900 rpm, pump 2900 rpm.

 

18 hours ago, w6kd said:

One more thought w/r/t your temps--make sure you have a good fan curve set up on that H115i.  One of my secondary boxes has a 7700K on an H110i, and the default fan curve is dismal--it does not even begin to keep up with the CPU when it gets loaded up.

I programmed the curve (using the Corsair Link software) to keep the fans at 500 rpm until 25 deg coolant temp, then ramp up to full speed at 30 deg C.  This avoids lots of speed shifting on the fans as the CPU temps fluctuate, and it responds fairly aggressively to actual heat in the system as it is loaded up.  If you're just using the default fan curve, it is not surprising that your temps spike high.

Regards

I even tried 100 % fixed mode, sir. No help.

 

17 hours ago, troyboy66 said:

Try increasing your temp to 1.350. I did an offset of 0.280 v. and I'm stable at 5.1 Ghz on all cores and never exceeds 70C. 

You mean voltage? Like said before, that is impossible with HT ON.

 

9 hours ago, martin-w said:

 

Theoretical max voltage for the 8700K is 1.5 volts. I'm not recommending that anyone use that voltage, as high temp is the obvious peril, just to give some perspective on why the OP's voltage is relatively low. 

My 8700K does 5 GHz on all cores at something like 1.34 volts I recall. It's delidded. Max it will do is 5.2 GHz at over 1.4 volts. 

That value is truly theoretical, I would not recommend this to anyone, as you massively reduce that life span of your chip at 1.5 V. Do you have HT ON or OFF?

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Rock solid 5.0 at 1.31v for my chip. (Avg temps at load are 68-71. Max I've recorded is 79ºC)

If you can keep temps under 85º increase your voltage.
 

 

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If your cpu is overheating above 1.20v then there is something wrong with your cooler. It's either not installed correctly or the TIM you are using is bad or your AIO pump is broken. You aren't going to get much going with 1.2v. You are lucky it's working at all at that voltage. Delidding will do nothing for you until you figure out what's going on with your cooler. Even the lamest of air coolers could do better than this at 1.2v. That cooler should easily be good enough for 1.35v or even more maybe. I know because my other machine uses an H80i single rad cooler and keeps my 6700k perfectly cool at 1.285v under prime load. It would probably do above 1.3v and it is a single rad cooler. Something is wrong with your cooler install.

Edited by J0nx
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15 minutes ago, J0nx said:

If your cpu is overheating above 1.20v then there is something wrong with your cooler. It's either not installed correctly or the TIM you are using is bad or your AIO pump is broken. You aren't going to get much going with 1.2v. You are lucky it's working at all at that voltage. Delidding will do nothing for you until you figure out what's going on with your cooler. Even the lamest of air coolers could do better than this at 1.2v. That cooler should easily be good enough for 1.35v or even more maybe. I know because my other machine uses an H80i single rad cooler and keeps my 6700k perfectly cool at 1.285v under prime load. It would probably do above 1.3v and it is a single rad cooler. Something is wrong with your cooler install.

The weird thing is that when I turn HT OFF, I can set it to 1.35 V easily and the temps are fine...

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I've had my 8700k running at 4.8ghz since I had it.  After reading other reports on here for the last few months, I've turned HT off and am now clocked at 5.0ghz.  As others have said, seems to run soooooo much smoother with it off.

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15 hours ago, Thomasso said:

I figured 🙂 The problem is that my CPU starts to overheat above 1.20 V with HT ON. There is just no way around it. I even pumped the H115i on 100 %, both fans and pump. Still massive overheating.

 

 

 

I'm surprised you are seeing overheating at a mere 1.2 volts. My 8700K is cooled with air, a Noctua NH-D15S. When you say "massive heating" precisely what core temp are you seeing measured with RealTemp or CoreTemp? And at what ambient temp.  And how are you stressing the CPU when you see that high temp? If you are running something like Prime 95 that runs AVX instruction sets then you will most definitely see very high temp. Aida 64 if you run FPU will run AVX! You must set an AVX offset.

You could have a hardware issue. Could be the mounting of your cold plate, fan issue, air in system, pump failure etc. Possibly your OC settings, if you have LLC set super high or something. 

 

Quote

That value is truly theoretical, I would not recommend this to anyone, as you massively reduce that life span of your chip at 1.5 V. Do you have HT ON or OFF?

 

As I said to you... "Theoretical max voltage for the 8700K is 1.5 volts. I'm not recommending that anyone use that voltage, as high temp is the obvious peril, just to give some perspective on why the OP's voltage is relatively low. " I was quoting this voltage as a comparison, your voltage compared to the max Intel recommend. 

 

I'm not currently overclocking at all, don't need to. But my recent test, cooling with the D15S, at an ambient of around 18C, resulted in 5 GHz with HT on, cant recall temps but quite reasonable. As an experiment to see what the chip could do, it manged 5.2 GHz with HT off.  I will try and track down the values, as I posted about it here. Voltage at 5.2 was 1.4. 

 

EDIT: These were my recent results with 8700K, delidded with Conductonaut. Maximus X Code, NH-D15S. 

 

I managed 5.2 GHz on all cores, at 1.4 volts. HT off. Temp was 79 degrees in Cinebench. Ambient was about 20C. With D15S. 

5.3 GHz failed and would have required close to 1.5 volts. Temp would have been too high too. 

 

 

 

Edited by martin-w

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13 hours ago, Thomasso said:

The weird thing is that when I turn HT OFF, I can set it to 1.35 V easily and the temps are fine...

 

it's not weird, HT on increases temp. Usually around ten degrees hotter with HT on. 

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4 hours ago, martin-w said:

 

it's not weird, HT on increases temp. Usually around ten degrees hotter with HT on. 

Yeah but I mean, if I have a hardware issue, it shouldn't handle even HT OFF, right?

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Going to pipe in here guys and tell you about my recent and similar issues with my 6700K.  For a long time I could easily run my system at 4.7 Ghz with HT on, (8 threads), I could also run P3D fine most of the time at 4.8 with HT off, voltages normally around 1.35 and up to 1.4 for 4.8 but recently temps started becoming abnormally high and I had no choice but to switch HT off completely.  Idle temps were sitting around 40 degrees yet used to be around 20 with a Corsair H100 AIO cooler.  I cleaned the cpu and cooler and reapplied new Arctic Silver, temps immediately dropped low again but after a day or two crept back up.  I knew I had a big problem when I could not even run my system at stock cpu speeds and voltages with HT on.  With the sim running my temps went over 90 degrees. 

It was then that I started reconfiguring my case and fans to try and improve airflow.  My Antec 1200 case is huge but not very modern and not great for water coolers and radiators.  It has 3 intake fans at the front but these are not working the best due to their age and at times the bearings rattle, I also have a ton of SSD's and SATA drives behind them in the drive racks which probably affects airflow.  There is a large 200mm plus extractor fan on top and was 2 120mm fans on the rear bringing air in.  The AIO could only fit on the back, was a very tight fit as case not really built for them.  As airflow coming in the front isnt great I configured the AIO with 4 fans, the 2 that came with it and two case fans attached to the other face, I set the fans to bring air in from outside the case, through the radiator then 2 fans pull hot air out into the case and out the extractor fan immediately above it.  All worked well enough until I noticed at times one case fan behind the AIO wasnt turning as clogged up.  I took the whole set up apart and decided to attempt to mount the AIO just below the top fan and just have 2 fans pull air from inside the case through the radiator then immediately out the case, I needed to make sure rear case fan was running at a higher speed.  Delved into my BIOS settings and changed them as they were on Quiet and fan never sped up in past which probably did not help my temps.  No mounting system to mount AIO below roof of case so I did a DIY job using cable ties to hold it there.  Im considering a new build so it wasnt viewed as a long term solution.  When looking for my instructions for cooler I noticed a Corsair Link cable which I never attached.  I used to have an older 120mm H80 which had a lead to attach to a hardware controller you install in a 5.25" bay so I had assumed this was the same thing.  When I googled it I realised it connected to a USB header and allowed control of the fans and pump via software so I sorted that out.  Load temps dropped by 30 degrees.  This was with the case on its side on the floor and side open.  Temps started creeping up as soon as I closed the case and put pc back into its normal position below the desk 😞

I was ready to throw the whole thing out the window, was seriously fed up so changed fans again back to almost the way they were originally, I binned the clogged fan so have 1x 120mm intake attached to the back of the case, the radiator attached to this then 2x 120 fans pulling air into case from radiator then out the top.  With aggressive fan speed settings it appears over the past couple of days to give very low temps, idles below 20 degrees, have registered a min temp on one core at 14 degrees and sim runs for hours and its peaking around 62 degrees but generally in 40s when simming.  I only bought my cooler 30 months ago and its been replaced within that time as a pump on the old one failed so I did not expect it all to have failed again.  Yours may be fine but its the arrangement of your case and fans which may need tweaked.  Can you describe how your cooling is set up, fans and direction of air movement?

Sorry for long post.

Chris

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7 hours ago, martin-w said:

 

I'm surprised you are seeing overheating at a mere 1.2 volts. My 8700K is cooled with air, a Noctua NH-D15S. When you say "massive heating" precisely what core temp are you seeing measured with RealTemp or CoreTemp? And at what ambient temp.  And how are you stressing the CPU when you see that high temp? If you are running something like Prime 95 that runs AVX instruction sets then you will most definitely see very high temp. Aida 64 if you run FPU will run AVX! You must set an AVX offset.

You could have a hardware issue. Could be the mounting of your cold plate, fan issue, air in system, pump failure etc. Possibly your OC settings, if you have LLC set super high or something. 

 

 

As I said to you... "Theoretical max voltage for the 8700K is 1.5 volts. I'm not recommending that anyone use that voltage, as high temp is the obvious peril, just to give some perspective on why the OP's voltage is relatively low. " I was quoting this voltage as a comparison, your voltage compared to the max Intel recommend. 

 

I'm not currently overclocking at all, don't need to. But my recent test, cooling with the D15S, at an ambient of around 18C, resulted in 5 GHz with HT on, cant recall temps but quite reasonable. As an experiment to see what the chip could do, it manged 5.2 GHz with HT off.  I will try and track down the values, as I posted about it here. Voltage at 5.2 was 1.4. 

 

EDIT: These were my recent results with 8700K, delidded with Conductonaut. Maximus X Code, NH-D15S. 

 

I managed 5.2 GHz on all cores, at 1.4 volts. HT off. Temp was 79 degrees in Cinebench. Ambient was about 20C. With D15S. 

5.3 GHz failed and would have required close to 1.5 volts. Temp would have been too high too. 

 

 

 

I measure the temps using Core Temp. Some cores go over 90C when I start stressing the system. Ambient temp might have been around 22C.

I use Prime95 and AIDA64 for testing. Did not alter any settings, no idea what AVX is 🙂.

I don't know about an HW issue... I remounted the thing multiple times, used after market Noctua paste. Pump is indicating 3000 rpm in Corsair Link software, fans are over 2000 rpm. I have no way to check if the cold plate is mounted correctly.

What is LLC?

 

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2 hours ago, Thomasso said:

I measure the temps using Core Temp. Some cores go over 90C when I start stressing the system. Ambient temp might have been around 22C.

I use Prime95 and AIDA64 for testing. Did not alter any settings, no idea what AVX is 🙂.

I don't know about an HW issue... I remounted the thing multiple times, used after market Noctua paste. Pump is indicating 3000 rpm in Corsair Link software, fans are over 2000 rpm. I have no way to check if the cold plate is mounted correctly.

What is LLC?

 

 

Okay... some synthetic stress tests like Aida 64 (with FPU ticked) and Prime95 will run AVX 2 instruction sets. AVX pushes the CPU to the absolute extreme, way beyond its normal level. Thus temps shoot up dramatically and can cause an overclocked CPU to throttle back and if it reaches TJ Max shut down.

Now the thing is, flight sim and games dont run AVX. Only stress tests run AVX and some applications like Handbrake for example.

Due to the AVX overheating issue, motherboard manufacturers include an AVX offset setting in the BIOS. Set it to 3 for example, and when the BIOS detects you are running AVX it will automatically down clock by 300 MHz and thus your CPU will not overheat. 

I suggest you set the AVX offset to 3, and also, if you intend to carry on using Aida64 to stress test, then DONT tick the FPU box. If you run Prime, download the older version that doesn't run AVX.

Following the advice above should solve your issue.

 

If you dont know what LLC (load line calibration) is and have never heard of AVX then you have very limited overclocking knowledge and should study some overclocking guides.

 

Good luck. 🙂

 

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