Skylake hard locks seeminly when IDLE / CStates ON

[GGlyn]

Myself and others have been struggling with a different hard lock problem with Skylake and we have ran out of options but to assume it is a CPU fault/issue. Does anyone have any comments or feedback?

The long thread is over here, but I will summarise. http://www.tomshardware.co.uk/forum/id-2830772/skylake-build-randomly-freezing-crashing/page-7.html New Skylake Build Randomly Freezing/Crashing - Page 7 - windows 10 - Windows 10

Our systems hard lock randomly but appears on the most part to be when IDLE or next to IDLE. The hardlock can come when playing video, browsing (reading) or mostly when not interacting at all. Some (like myself) noted that they seem to occur more often if you are doing a large amount of disk IO (partition move for example or copying 40+ GB of data disk to disk).

Hard locks happen in either Windows (7,8,10) or Linux.

With CStates on, the crashes are often and usually within 10 minutes of IDLE. With CStates disabled completely most find that the system remains "mainly" stable for days. Generally, no one has reported locks when gaming or under high CPU load (so I do not think this is the Prime95 example but then, since compilers / drivers use the latest instructions (according to CPUID) I cant be sure).

The symptoms happen on many different manufacturers motherboards, RAM types and setups. We have successfully removed or replaced all components and the only change that seems to make a difference is CPU for a few. CStates off in the BIOS is absolutely a guarenteed way to stabilize significantly but not fix.

I changed CPU (after trying everything else) and find it now mostly stable with CStates ON. I must be clear that my system is 100% identical, CPU # 1 crashes all the time and must have CStates off, CPU # 2 does not crash so often even with CStates ON. One may argue this is a problem with my PC, a fault, but with so many people having the exact same issues I cant believe it is a defect. And with Cstates/SpeedStep so specifically (a known new part of Skylakes architecture), I remain convinced that this is something real.

Others were not so lucky, a replacement CPU did not make the situation better. Batches from different factories as well etc etc

My new CPU has hard locked but not when IDLE like the last one (not yet anyway). Mine can lock when under full load, video transcoding, but not more than 1 in 10 sessions. Cstates ON seems equally stable on this CPU as OFF.

Thanks for any suggestions you can give.

[satas]

No idea what they really do but this tweak mode was more or less my last hope. now I'll either stick to the spd with 2133mhz or try another brand of ram. I'm tired of wasting my time troubleshooting and testing instead of doing my actual work.

[CCris2]

I'm afraid that if you buy another ram like g.skill, you will have same problems. Before I bought my ram I looked on internet on newegg and other sites, about what people were saying about different types of ram and some of them were complaining about g.skill, that they have stability problems or not working in XMP mode, so i think this whole thing is about mainboard. If you gonna order them again on internet, without testing, you may end up with same problem.

[satas]

I'm afraid of that too, but there is no single solution for all.

if I had the chance I would buy the cpu, ram and motherboard in a shop after testing them.

but no chance here to do that, and no Puget Systems or Origin around.

[CCris2]

Another Asus mainboard bites the dust

[MBell11]

No I haven't tried the maximus setting yet. And I don't have any BSOD issue by the way.

For now I'm testing the fast boot disabled thing (in both windows and bios) since a few people said it fixed their problem, and I also installed the latest chipset driver. If I freeze again, I don't think I will even bother, and I will replace my CPU and MB. For now, 12 days without a freeze with all c states enabled, which does not mean anything since I already went 4 weeks without a single freeze in April, and then freezed once.

[LMonk]

So i can report something. As i already metioned i disabled cstates completely, disabled svid, my cpu voltage after all is ~1.184, bclk at 102, frequency scaling is about 50% in windows, so now my lowest freq is 1852MHz. So i reached first time 13 days of uptime and there was blackout. Second time i reached almost 22 days and i thought my instability was fixed. But i had hard lock in idle when i was asleep. It was my worst morning in this year =/. I will rma my cpu i gave up.

[CCris2]

Hi lks70

I have mainboard on which I have usb and sata asmedia controllers, only sata controller drivers are creating problems.I have a question. What CPU and mainboard you have ? If your bclk is 102, your min frequency shoud be 8x102 = 816 Mhz or 10x102 = 1020 and not 1852. o.O

There is something wrong in your settings.

[LMonk]

I set minimum limitation cpu by os to 50% and i noticed that 1852MHz was minimum freq. Now i experiment with 103.

[MBell11]

Update : in my case, it was not a C state problem.

Last friday, I suddenly had 3 hard locks out of nowhere and could replicate it easily by watching a video, within 5 minutes it would crash (not related to power / sleep settings), so I grabbed that opportunity to try a few things in the BIOS, including disabling c states, speedstep etc. which did not have any effect.

In fact, my problem was that I had adaptive voltage on (no overcloking though) with almost no positive offset, which could actually explain occasional instability at light load / idle, my vcore was in fact too low at idle / low load. I read this a few days ago on a forum, apparently it happens a lot with Skylake.

I applied a positive offset of 0.05v and it has been stable ever since. I let my PC read a movie in loop for 2 days, with c states on, and no crash. It's also stable on optimized settings (vcore on auto).

I feel really silly for not testing with manual or auto vcore, I was so convinced by reading this thread that it was a C state issue... I am so dumb for not testing the optimized settings in the Bios first...

Anyway, I hope you guys will solve your problem, thanks for the help.

[CCris2]

Hi Berdugo

So Asus undervolted or lowered the current of the CPU to look good in power consumption benchmarks, thats why so many problems on asus mainboards. Some CPUs simply don't work at those voltage/current. They need just a little bit more.

[LMonk]

Maybe somebody will help me. In my case i always get freeze around 5+ days. And i can't get why. I run so many test, and i never got instability. I have only instability when i set bad configuration - too low voltage or too hight freq etc. So i wonder why i even hard lock? I always use virtual machines, can this be a problem? I don't do nothing special on my machine, only virtualization. I need another test vector or something? I think maybe i can do 24/7 memtest86 at first? And try to do it for more time then my typical uptime before hard lock?

[CCris2]

First of all tell me your system configuration, because all I know is that you have instability problem.

[LMonk]

Currently i run this on default optimized settings, last uptime was around 5 days and hard lock with looping distorted sound.

ASUS Z170-K

BIOS verson 704

BIOS version 704

Nvidia 660 GTX

CPU i5 6600k

Ram CORSAIR Vengeance LPX CMK16GX4M2A2133C13 DDR4 2x 8Гб

OS Windows 10 64bit

I tried different configurations, different oses for example gentoo, ubuntu. Everywhere equal problem "hard lock". In my cases it is always around 5+ days. All my setups used vt-x at least, on gentoo and ubuntu i use vt-d. Can be virtualization be a problem? I do this because of my job, i need linux. And i use windows to play games. Maybe i need to try my cpu without any virtualization? I need just another test vector as i said. I didn't rma my cpu because i can't reprodice error that easy. I am i fear that they will just return me my cpu after 40+ days. Thinking about buying equal one with later batch.

[CCris2]

Do a bios reset first.

Update bios and don't load any default settings. Here is new bios: http://dlcdnet.asus.com/pub/ASUS/mb/LGA1151/Z170-K/Z170-K-ASUS-1803.zip?_ga=1.261291853.1393409749.1463692318 http://dlcdnet.asus.com/pub/ASUS/mb/LGA1151/Z170-K/Z170-K-ASUS-1803.zip?_ga=1.261291853.1393409749.1463692318

Enable CPU voltage to adaptive and set memory to XMP .

[LMonk]

Did not see that bios coming. Thought my is latest. Cat i enable vt-d ?

[CCris2]

Yes, on my mainboard is enabled by default

[LMonk]

But what about test vector? I just can't wait another hard lock I am so tired.

[CCris2]

The new bios and making the settings I told you may fix your problem.

The bios you had is very old.

You updated bios ?

[CCris2]

I have a question.

When system was hard locking it was idle or you were doing something on it ?

[LMonk]

How do you think, we can say that system running virtualbox with linux and twitch.tv in host browser is idle or not? Last time i was standing in few meters near pc. I can say that i did not send input to my pc, that's all i think. I remember when it hard locks in game or in middle of my user session. I updated bios as you said, set just addaptive voltage with auto values, disabled integrated video card and enabled vt-x. Thinking about running few tests now. And maybe come back and bump voltage.

[CCris2]

For now don't bump any voltage. Leave it as it is because on the bios they fixed some compatibility and stability issues with memory I think. We need to see if it is stable. Do tests like for example open 50 youtube video pages, and run them for like 15 minutes at least