Simple instructions for freezing a Skylake Processor.

[HStok]

The people at the community over at http://www.mersenneforum.org http://www.mersenneforum.org have found what appears to be a bug in the new Skylake architecture that can freeze any system that has a Skylake processor.

The Mersenne community are a bunch of mathematicians and other folks that use Intel processors to find record prime numbers. They have found all the record prime numbers of the last 20 years.

The main website of the community is http://www.mersenne.org http://www.mersenne.org where they keep track of all progress in searching for a new record prime number.

Owners of Skylake systems have found out that the software package that they use to hunt for prime numbers will freeze their system if they use particular settings. Since this bug is reproducible and has been confirmed on motherboards of many different suppliers and with RAM modules of different suppliers the bug seems to be tied to the processor architecture. The bug is reproducible under Windows and Linux.

This software works perfectly normal on all other Intel processors of past generations.

Steps to freeze your Skylake system:

- Download and install Prime95 for Windows on a Skylake system from the website at http://www.mersenne.org/download/ http://www.mersenne.org/download/

(If you want to familiarize yourself with the software use the readme, a background in math will be helpful, but is not needed.)

- In the menu go to 'Advanced | Test' and fill in the number 14942209 in the box labeled 'Exponent to test'

- Let the program run for some time and at some point, minutes or hours, the system will freeze.

The prime95 software does multiplications of extreme high numbers using the Fast Fourier Transformation. The implementation of these FFT's in prime95 is handcoded in assembly by George Woltman, and is the most efficient implementation available. This project runs for more than 20 years now and has always been carefully maintained. Tens of thousands of machines run this software 24 hours a day.

For optimization, different FFT sizes have been implemented in Prime95, only the FFT with length 768K freezes the Skylake.

It is my fear that like the infamous FDIV bug this issue will require a new stepping and a product recall, since this has security implications as well.

If you have a Skylake system I invite you to try out the steps above. Please post your findings here and in the mersenneforum at http://mersenneforum.org/showthread.php?t=20714 http://mersenneforum.org/showthread.php?t=20714

Regards,

[Cesar_B_Intel]

Hello All,

Original equipment manufacturers are aware of issue. In this case please contact the system manufacturer for the latest system BIOS updates.

Regards,

Caesar B_Intel.

[CHals]

Thank you for the update Mr. Badilla.

I have taken the liberty of reposting your message over on the Mersenne Forum, so people following over there know they should contact their motherboard suppliers for the appropriate BIOS upgrade.

Sincerely, thank you and everyone at Intel for working and solving this issue so quickly.

Kindest regards.

-Chris

[Cesar_B_Intel]

Hello Chris_Halsall,

Thank you for sharing the information in the Mersenne Forum* we hope this information helps others, too.

Regards,

Caesar B_Intel.

*Other names and brands may be claimed as the property of others.

[idata]

Hi orlich,

Regarding this issue, is there any information in specification update? Or if Intel release any document to explain it? Thank you.

[idata]

Hello Terry

As part of Intel's regular communication process, the next specification update is targeted for publication by end of this month. This update will include information on this issue.

[CDura1]

Hello,

I am having the same issues.. seems like MSI put out a fix for this already but other companies didn't.. im with ASUS and no news.. seems like they don't even know about the problem.

Please give us an update of WHEN manufacturers are getting the BIOS update.. this is really frustrating!

[Ronny_G_Intel]

Terry Yang, Chris Halsall et all,

The http://www.intel.com/content/www/us/en/processors/core/desktop-6th-gen-core-family-spec-update.html Specification update has been updated and includes information on this issue. Please refer to SKL082 (Processor May Hang or Cause Unpredictable System Behavior)

Regards,

[clope14]

I am having random freezes with a Skylake Xeon E3-1535M that is already runinng with 0x74 microcode:

$ head -26 /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 94 model name : Intel(R) Xeon(R) CPU E3-1535M v5 @ 2.90GHz stepping : 3 microcode : 0x74 cpu MHz : 2901.000 cache size : 8192 KB physical id : 0 siblings : 8 core id : 0 cpu cores : 4 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 22 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c lahf_lm abm 3dnowprefetch ida arat epb pln pts dtherm hwp hwp_notify hwp_act_window hwp_epp intel_pt tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 hle avx2 smep bmi2 erms invpcid rtm mpx adx smap clflushopt xsaveopt xsavec xgetbv1 bugs : bogomips : 5807.83 clflush size : 64 cache_alignment : 64 address sizes : 39 bits physical, 48 bits virtual power management:

The freezes happen randomly when the computer is under full load for several minutes (ex: Building a large C++ project like WebKit)

The computer is a Dell Inspiron 7510 with 16GB ECC DDR4 RAM.

[Ronny_G_Intel]

Hello All,

I work for Intel Customer Support and just wanted to let you know that Intel will be publishing the next specification update in February following an update to our publication process.

This specification update will include information on this issue. No other additional information for now.

Regards,

[OSten2]

You should get your live support more informed about this, had to spend one hour just to convince them there was a known "bug" with skylake processors.

Are you planning on doing any changes to the manufacturing of these?

[dmone2]

*below is my response in an Intel forum thread going on right now that i have no doubt is related to this freezing problem. not sure how the geniuses over at mersenne stumbled on it running Prime because I can run Prime no problem, but God forbid I right click on a desktop folder... hang city baby...

*27. Re: Skylake hard locks seeminly when IDLE / CStates ON

"kinda glad i found this thread. stupid new skylake build randomly hangs for 5-30sec at a time...all the time. after the hang it will right itself and i never get BSOD and i have not had to hard reboot. ram is good, ram voltage is good, cpu (i7-6700k) oc'd to 4.4 can run marathon circles around prime for days on end, but the moment i start dragging and dropping files on desktop, opening Word, Word Perfect, Adobe Pro, VideoPad Video Editor and ImageEditor, copying and pasting...i get frequent random hangs. it sucks. this is a NEW pc build. like, literally 3 days new and a fresh Windows 10 install, not upgrade. playing with C-states did not increase stability, it happens whether i run with oc or stock, happens whether XMP is on or not, slight adjustments to voltage (cpu or dram) do not help. please someone tell me that Intel is all over this problem and that a fix is coming. i will RMA if not resolved in the next week or so. i have things that need to get done. thank you to those here who provide technical assistance to us noobs. you are appreciated."

i7-6700k

AMD R9-390 8GB GDDR5

Corsair H55 w/ Fractal high performance fans

Gigabyte Z170XP-SLI (running latest bios update)

ADATA XPG Z1 16GB DDR4 2800

Sandisk 400S SSD

WD Caviar Blue 1TB HDD

Thermaltake Smart 750w PCBUS

[Ronny_G_Intel]

Hello dope money,

I would recommend that you check or post under the following community thread: I believe this community is more appropriate for your comment. This thread is only for Skylake Processors exhibiting issues when running Prime95*

Regards,

[dmone2]

Thanks, i have posted to that thread long before i posted here. I am not certain I understand, did you begin a thread on a known Intel issue? Intel has already released a statement regarding chips failing after 1,000,000 hours of Prime (or whatever crazy number they came up with). I was trying to help out in case you mis-diagnosed your issue. sorry about any misunderstandings! good luck to you.

[JGiat]

I'm the owner of the link

http://giatrakis.wix.com/john-giatrakis http://giatrakis.wix.com/john-giatrakis

and this is saying it all, almost all.I did dumped intel permanently the day they did publised the new cpu Haswell-e cpu's i7-5960X, i7-5930k and i7-5820K I was so happy that intel fixed a processor the way i said (fully soldred processor) but the happiness stoped in minites when i realized they did put inside the new chip a voltage regurator (they producing heat 105 c) and the northbridge +80 c!? I was sure the most cpu coolers will fail to control the tempratre of these cpu's in higher overclock. They also did trupt the cpu between 2 memory dimms making the airflow to the regulators almost impossible to get even from NH-D14!? I was sure intel was trying to destroy all my planning as i couldn't find 1 new motherboard to publich at my page and say this is it for the new chip!? Now they released a cpu that does not run prime95, practicly you have a cpu that can not add some prime numbers and you wait a 'fix' that will create fake results in prime?

What do you wait RMA their stupid 'products'. I moved to opteron a cpu that is used to supercomputers and in servers.In there there is no room for 'mistakes' and 'jokes' and i had enough WHAT I MEAN REALLY HAD ENOUGH.