i5-6600K overclock resulting in BSODs beyond 4.2 GHz

[saihv]

Hi, my PC has an i5-6600K, Cooler Master Hyper 212 EVO, 2133 MHz DDR4 8 GB RAM and an MSI Z170A Gaming Pro MB and an R9 390 GPU. Before attempting overclocking, Prime 95, Intel Burn test, Furmark and Memtest were all stable.

Here's what I tried during overclocking:

1. Increase Vcore to 1.275 V, set multiplier to x42, default BCLK (4.2 GHz)

Prime95 stable for 30 minutes, Intel Burn Test stable for 10 passes on very high, temps were around 63, 68, 64, 61 for 4 cores.

2. Increase Vcore to 1.300 V, set multiplier to x45, default BCLK.

As soon as I tried to sign in into WIndows, I got a BAD_POOL_HEADER BSOD.

3. Keep Vcore at 1.300 V, set multipler to x44.

Sign in successful, Prime95 stable at similar temperatures. Tried to run Cinebench and got a CLOCK_WATCHDOG_TIMEOUT BSOD.

4. Increase Vcore to 1.35 V, set multipler to x45.

Sign in successful, Prime95 stable at slightly higher temperatures: 67, 71, 68, 64. Tried to run Cinebench and got a CLOCK_WATCHDOG_TIMEOUT BSOD.

So currently I am at 4.2 GHz with 1.275 V. My plan was to get it up to 4.5, but I am probably doing something wrong here? Looks like it's not high temperatures: but then again, my overclocking knowledge comes from a random assortment of forum posts and Youtube videos. Any comments or suggestions would be very helpful, thanks!

 

[Eximo]

You should probably read through an actual overclocking guide. Additionally is the only thing you are modifying the core voltage? A little more to it then that: http://www.overclock.net/t/1570313/skylake-overclocking-guide-with-statistics

They don't cover very much here honestly, but they do have results from lots of people.

What are you setting Vin to? Generally need to bump it up .1-.2 volts for overclocking.

Here are some more robust older guides for the Haswell chips (same guy). Much will be similar:

http://www.overclock.net/t/1411077/haswell-overclocking-guide-with-statistics

My favorite guide since it explains what everything is and does:
http://www.overclock.net/t/1401976/the-gigabyte-z87-haswell-overclocking-oc-guide

 

[saihv]

Thanks, that's a great guide. Currently I'm able to hit 4.4 GHz at 1.32 V. Perhaps 4.5 needs more than 1.35.. Also, when I'm running Prime95 on this overclocked cpu, the frequencies stay at 3.6 to 3.7 GHz most of the time.. How realistic of a stress test is it then?

 

[Eximo]

If it is throttling itself below your set speed, it is likely overheating. Also sounds like you haven't changed the power saving features and aren't using an offset overclock. When you are first starting out you want to remove as many variables as possible. Disable all the C-states and set voltages manually. This will let you observe a constant voltage/temperature under load to see what the chip can really handle.

Depending on which Prime95 you are using (the latest versions are quite unrealistic) (Though I personally like the unrealistic tests, makes me very confident about stability)

1.32 volts is quite a lot actually, I don't even run my 22nm chip at that, yours is 14nm and should really run at lower voltages (Though they say 1.4 is safe, that seems extreme and likely involves high performance water cooling). Hyper Evo is a good cooler for moderate overclocks, not really the top numbers. 4.4 Ghz is quite respectable.

I would say keep it under 1.3volts for temperature, bump the Vin up a little, look into load line calibration. If you haven't already, disable the onboard video. Crashes can be caused by too much temperature or too little voltage for a given load. The trick is to find the balance point of your specific chip and cooling solution.

Since I haven't picked up a Skylake chip, and probably won't, I can really only relate information gleaned from the Haswell and Devil's Canyon chips. I've built and overclocked a few systems with those.

Skylake to me is a hybrid chip, two memory controllers for a start, and the motherboards are between too many upcoming technologies. Probably upgrade to the next E-class chip myself.

 

[saihv]

At 3.7 GHz which seems to be the sweet spot for Prime95, my current temperatures on all four cores are around 65-70 deg C: so I thought it would definitely have more room to increase the clocks. And Cinebench for example has no issues taking it up to 4.4.

 

[Eximo]

Not really, those are the nominal temperatures to shoot for. Anything above 80C would be considered a lack of adequate cooling. If it isn't running at the speeds you have specified, then you aren't really overclocking it.

What does the core voltage read when it is at 3.7Ghz under load? (CPU-Z, Hardware Monitor, Hardware Info are useful tools here)

If you are forcing the voltage to be fixed and the core clock is reducing itself then the voltage is probably too high. If the voltage is still being controlled by the CPU, then something is not set up correctly.

Here are my old results:
i7-4770k Vin 2.0 Vcore 1.35 + Tuniq Tower 120 Extreme 100C peak (4.5Ghz) stable but way too hot
i7-4770k Vin 1.9 Vcore 1.31 + Tuniq Tower 120 Extreme 88C peak (4.5Ghz) unstable

Inbetween here I tried BCLK overclocking and tweaking, just doesn't really like running above 4.3Ghz with maximum stability.

i7-4770k Vin 1.8 Vcore 1.2894 + Tuniq Tower 120 Extreme 73C average 77C peak (4.3Ghz) stable
i7-4770k Vin 1.8 Vcore 1.2894 + Corsair H80i 77C average 81C peak (4.3Ghz) stable
i7-4770k Vin 1.8 Vcore 1.2894 + Swiftech H240X 63C average 67C peak (4.3Ghz) stable + 2 GPUs in the loop.

 

[saihv]

Here are my current BIOS settings if it helps.

http://m.imgur.com/P5uR3KN,ixTD3tQ

EDIT: core voltage drops to 1.248 when Prime95 is running as measured by HWINFO. Speeds go up to 4.4 during normal usage. I ran Fire strike (not really a "stress" test) and the speeds reached 4.4 and the maximum temperatures were 68, 74, 69 and 67.

 

[Eximo]

I think Dynamic mode is your culprit for the lower frequencies when under huge stress. If it is running at 4.4Ghz when you game, then that is okay. I just have mine set at fixed so I know it is always running at the desired speed. Though under some circumstances the CPU might still throttle and result in stuttering (map loads and transitions from rendering zones might be noticeable)

Core voltage mode/GT Mode is likely what is reducing the voltage from your maximum setting.

Not seeing a CPU input voltage, so that might be automated now. I do recall reading that they took the VRMs off of the CPU this time around and rely on the motherboard, so maybe they just supply core voltage directly like back in the day.

Looks like a lot of people are getting that 1.4 volt figure from HardOCP's review. They aren't going for longevity, just maximum overclocks and they managed a stable 4.7Ghz with an i7.

 

[saihv]

Gotcha. That makes sense. I honestly don't mind, because all of the benchmarks resulted in higher scores so there's definitely some on demand overclock going on. How would a fixed voltage affect the long term operation of the CPU? To me really, 4.2 to 4.4 GHz is a decent enough overclock , I am more concerned about longevity than a few extra fps so I'd rather stop at the point where the manual changes such as voltage vs returns curve tends to saturate.

PS when I am comfortable with my stress test results etc , can I turn speed step back on?

 

[Eximo]

Been running my i7 overclocked since day one, June 2013 I think. Zero issues so far. Now yours is built on an even smaller node, so longevity might be slightly reduced, but I generally replace CPUs before it ever becomes a problem. My i7-950 is still kicking around, but I simultaneously overclocked and undervolted since it was such a good chip (My RAM couldn't keep up). I also aim for longevity though. I don't need an extreme overclock, just a little free performance and the fun of finding a good balance point. I haven't tried overclocking it further since I switched to custom loop cooling, I know the chip can run at 4.5Ghz at least and cooling was my issue then, but I really don't want to hover around the safe maximum voltage to do it.

Speed step and offsets can be used to have overclocked performance and low idle power consumption, that is what they are designed for. I don't use them because when that computer is on, it is running something.