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.

[CCris2]

The memory, vccsa and vccio voltage you modify when system is not stable at default, not overclocked.

[EKnya]

Auto. Which is sets vcore to whatever it thinks appropriate.

Normal. Which is what i use right now - it allows you to setup offset.

Manual, which is just overwrites vcore to whatever you set.

I would pretty much like to stay with this normal-offset mode as it doesnt make vcore go sky-high at idle and keeps stable voltage under stress loads.

I am going to monitor how it all goes after bios flash and report back if anything like that happens again - just the though it might be "incompatible" ram makes me wanna vomit. Its just a stick of ram for gods sake..

[CCris2]

If you disabled Intel Speed Step your cpu will need almost the same voltage when idle and under load. If you enable speed step, CPU when idlen will have only 800Mhz, and the voltage should be 0.7- 0.9V max .

Its strange that it has only 2 llc levels .On Asus there are 8 llc lvls and on asrock 5 llc levels.

Can you set offset voltage at least ?

[EKnya]

Yes, i already said i can set offset, +0.040v makes for stable 1.356v under load.

Also i just set everything related to power saving on AUTO and it works just fine, no overvoltage on idle.

[PMan]

Hello everyone,

finally my problem was solved as follows :

Intel has been very professional and agreed to replace my NUC.

DHL picked my NUC and has delivered another one in less than three days and for free !!

So i installed the SSD M2 and the RAM.

The new NUC started without problem... BUT... froze in less than five minutes

I decided to install W7 instead of W10.

It was not easy as there are only USB 3.0 ports on the NUC.

I tried using the Intel Application "Windows 7 USB 3.0 Image Creator Utility" but impossible to change my W7 image.

https://downloadcenter.intel.com/download/25476/Windows-7-USB-3-0-Creator-Utility Download Windows 7* USB 3.0 Creator Utility

Fortunately with the asrock tool it worked

https://www.youtube.com/watch?v=d_zPIGrFypI How to install Windows 7 on Skylake platform using USB device - YouTube

I made a bootable USB drive with the rufus tool

http://rufus.akeo.ie/?locale=en_US Rufus - Create bootable USB drives the easy way

W7 install passed without problem.

AND THEN, MIRACLE... THE NUC HAS NEVER FROZEN

Then i migrated W10.. AND... THE NUC HAS NEVER FROZEN !

So I think it's important not to install W10 directly but first install W7 !!

I hope my experience can help.

Thank you all for your advices.

[CCris2]

Did you install any drivers on windows 7, except the usb 3.0 ? because, before, for me it seems like you skipped some driver install on windows 10.

[PMan]

Hi Ronin,

i made the same installation on W7 than W10.

The only drivers added on W7 were usb 3.0.

[JKapp1]

Chiming in here with my setup. System is unstable at any voltage setting unless I disable all c-states

Motherboard: Gigabyte z170mx-gaming-5 (Tested with bios f5e, f4, f3)

CPU: 6600k (running at stock frequency and voltages)

Video: evga gtx1070 (tried with and without video card, no difference)Memory: Corsair vengeance lpx CMK16GX4M@B3200C (running at 2133, 1.22volts)

PSU: 750watt corsair, also tried 430watt unit without using the video card, no diffrence

I tried many different settings for voltages for vcore, vccio, dram, etc. Only thing that has worked so far is disabling all c-states. With my current settings, if I enable c-states I will get a hard lock within 30 seconds of booting windows, like clockwork.

I'm afraid to RMA this chip as it doesn't seem like Intel has identified what the actual problem is.

[CCris2]

Hi d1981,

There are people who changed CPUs and memories and in the end it was mainboard. There are people who changed CPU or memory and it worked.

Most of the times it is the mainboard not setting CPU voltages correctly. Normally if everything is on auto and CPU on Normal voltage it should work without any problem.

If you don't have CPU voltage to normal set it on normal. After that please post a ss with voltages in HWiNFO.

Also be sure that memory in not with activated xmp, and post again the memory model because is not full.

[JKapp1]

This first screenshot is with the settings that worked for me, all c-states disabled, ddr voltage bumped to 1.24 and vccio bumped to 1.15. No lockups.

I tried again with setting the cpu voltage to 'normal' and everything back to auto with c-states enabled. Crashed within 30 seconds of booting windows. Had to take the screenshot with my phone.

And my microcode is MU065E0374

[abarb]

Intel, please, recall all skylake's. Bugs bugs and more bugs...

[CCris2]

d1981 ,

The memory you have is CL 15 or CL 16 at 3200 ?

[JKapp1]

@Ronin, it's CL16 at 3200. Timings from the QVL pdf for 3200 are 16-18-18-36 at1.35v, which the board does set correctly with xmp enabled.

[CCris2]

I think there is something wrong with mainboard or CPU. I have an Asrock mainboard z170 extreme 7+ and I never have so low voltage on minimum. It seems that your mainboard undervolts the CPU when you set everything on auto and CPU normal voltage.

i5 6600k works in idle CPU multiplier x8 and under load CPU multiplier x35, and if not so busy, it pushes up to x39. In idle the minimum voltage is about 0.720V and under load about 1.2V.

If the minimum voltage is to low the CPU crashes, or freezes.

When you disable c-states you force CPU to work at maximum all time ...

I have the same memory as you, by the way, and if you look few pages before this, you will see exactly what VCCSA, VCCIO and other voltages are on my CPU with XMP enabled.

[JKapp1]

I've seen the vcore value in hwinfo at 0 volts as minimum. I'm currently running with vcore voltages set to 'normal' and dynamic vcore set to +.05.

I also turned off a gigabyte setting called 'voltage optimization'. I've seen it described as a way to reduce power consumption and figured it might be the cause of undervolting.

So far with these settings and c-states enabled I haven't seen any crashes in 2 hours of use. My vcore current value according to hwinfo is hovering around .1 - .8 volts. VID minimum for any core is 1.096.

[ssote]

d1981 wrote:

I've seen the vcore value in hwinfo at 0 volts as minimum. I'm currently running with vcore voltages set to 'normal' and dynamic vcore set to +.05.

I also turned off a gigabyte setting called 'voltage optimization'. I've seen it described as a way to reduce power consumption and figured it might be the cause of undervolting.

So far with these settings and c-states enabled I haven't seen any crashes in 2 hours of use. My vcore current value according to hwinfo is hovering around .1 - .8 volts. VID minimum for any core is 1.096.

Have you tried using the Intel Processor Diagnostic Tool? https://downloadcenter.intel.com/download/19792 Download Intel® Processor Diagnostic Tool

[CCris2]

Can you look in bios at HW monitoring at CPU Vcore. I think that HWiNFO readings are not so accurate.

[ssote]

d1981 wrote:

Chiming in here with my setup. System is unstable at any voltage setting unless I disable all c-states

Motherboard: Gigabyte z170mx-gaming-5 (Tested with bios f5e, f4, f3)

CPU: 6600k (running at stock frequency and voltages)

Video: evga gtx1070 (tried with and without video card, no difference)Memory: Corsair vengeance lpx CMK16GX4M@B3200C (running at 2133, 1.22volts)

PSU: 750watt corsair, also tried 430watt unit without using the video card, no diffrence

I tried many different settings for voltages for vcore, vccio, dram, etc. Only thing that has worked so far is disabling all c-states. With my current settings, if I enable c-states I will get a hard lock within 30 seconds of booting windows, like clockwork.

I'm afraid to RMA this chip as it doesn't seem like Intel has identified what the actual problem is.

Intel will cross ship the cpu so you don't have to go without.

[CCris2]

wingman99 You have also a gigabyte mb. Do you have also min voltage so low on CPU ? ... 0.192 V

[PJohn10]

Hi all. Just thought I'd add my info here.

This has to be the most maddening troubleshooting job I've ever been involved with in my life. To say that I'm disappointed in Intel for this would be a gross understatement. Because of the inconsistency of this bug, I've misdiagnosed it as a bad video card and motherboard and replaced both. I only stumbled across this thread after I began to suspect the processor, played with bios settings, found the increased stability, and googled the right combination of phrases.

This problem is an instability nightmare. Hard locks followed by bios loop booting, computer not recognizing my boot drive, complete unpredictability, erratic symptoms, and times where my computer is literally useless. All because of a widespread, well-known issue with Intel's flagship processors? The fact that Intel has not done more to recall or rectify this makes me seriously consider never purchasing an Intel processor again.

Now that I have that out of my system: Disabling C states has me able to boot consistently and seems to have greatly increased system stability. That others have replaced their processors and still not had success is astounding. I myself purchased this processor as part of a pre-built ASUS system, so I cannot even go through Intel for warranty service.

Intel needs to do something to fix this now. Whether it's a software update or a recall. Anything less than a complete fix is absolutely disrespectful of its customers.

[CCris2]

Hi PhillyJ ,

Actually I never had any of these freeze issues, and some people, who replaced mainboard with other manufacturer got problems fixed.

From what i saw most people have problems with Asus skylake mainboards , not setting XMP correctly or even worse, on auto mainboard having some voltage problems.

I don't know what is really wrong on these mainboards, but even after bios updates they don't work how they should, and that means that there is a hardware problem somewhere.

CPU simply reacts to what voltage and settings, mainboard sets for it.

The only problems I have are with the igpu, because the driver is not yet fully working with some games, but I had some good news that Intel is working on it.

In your case, what you can do, is go with system in service.