Skylake Users must read this

Printed From: ASRock.com
Category: Technical Support
Forum Name: Intel Motherboards
Forum Description: Question about ASRock Intel Motherboards
URL: https://forum.asrock.com/forum_posts.asp?TID=1719
Printed Date: 25 Dec 2024 at 1:13pm
Software Version: Web Wiz Forums 12.04 - http://www.webwizforums.com

Topic: Skylake Users must read this

Posted By: wardog
Subject: Skylake Users must read this
Date Posted: 12 Jan 2016 at 10:41pm

This has already been questioned here in the forums, re: Prime95 throwing errors but system runs great, so I thought it best to post notice on all you Skylake Users

Skylake Bugs Aren't Odd, They're Prime (Posted Jan 11 2016)

http://www.tomshardware.com/news/skylake-prime-number-bug,30979.html" rel="nofollow - http://www.tomshardware.com/news/skylake-prime-number-bug,30979.html

A Short snippet blatantly heisted and then posted here from the above link:

Originally posted by Over at TomsHardware.com is

Over at TomsHardware.com is wrote:

Intel discovered that its latest 6th Gen (Skylake) Core processors have a bug that can cause the system to freeze or crash when calculating prime numbers.

While testing Skylake processors with Prime95, a few testers observed that the system would on rare occasions freeze. The bug is not limited to Prime95; it may also affect compute-intensive programs such as scientific and financial applications. This problem affects all Skylake processors ranging from the low-end Core M up to the top-end Xeon CPUs.

Replies:

Posted By: parsec
Date Posted: 12 Jan 2016 at 11:09pm

This bug is caused by running AVX (NOT AVX2) instructions in Prime 95.

Takes at least a two hour run of Prime 95 to cause the bug to occur, which will freeze the Prime 95 run. You may literally need to force Prime 95 to run the AVX instructions by setting a flag in the Prime 95 option file. The flag and setting is: FMA3 = 0. I know, how is that related to AVX? You tell me...

The AVX instructions are apparently so rare or non-existent in most real world applications, that it is never noticed outside of running Prime 95.

There seems to be some question regarding whether or not this applies to all Skylake processors. The i7-6700K is known to be affected by this bug, but I did not see information about others.

Intel is not letting this slide by as an "errata" bug that they won't fix, which is a good thing. It's also a bug that can be fixed in a microcode update. Thumbs Up

So this is NOT a permanent bug in Skylake processors.

UEFI/BIOS fixes for this situation are pending from mother board manufactures, but apparently Intel has provided the new microcode to them now.

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