Tuesday, January 12th 2016
Intel Core Skylake Processors Freeze Under Certain Workloads, Company Issues Fix
Intel's 6th generation Core "Skylake" architecture is faced with a major bug. Responding to a support question on its Communities page, on how certain multi-threaded stress tests like Prime95 can cause the system to freeze; Intel confirmed that an issue affects all 6th generation Core products. In certain highly-specific workloads, such as Prime95, "Skylake" chips hang or cause "unpredictable behavior."
Intel stated that it identified the issue and has released a fix. The company is working with its motherboard partners to get the fix across to users through a system BIOS update:
Intel stated that it identified the issue and has released a fix. The company is working with its motherboard partners to get the fix across to users through a system BIOS update:
Intel has identified an issue that potentially affects the 6th Gen Intel Core family of products. This issue only occurs under certain complex workload conditions, like those that may be encountered when running applications like Prime95. In those cases, the processor may hang or cause unpredictable system behavior. Intel has identified and released a fix and is working with external business partners to get the fix deployed through BIOS.
34 Comments on Intel Core Skylake Processors Freeze Under Certain Workloads, Company Issues Fix
Just a thought... I for one have never had Prime95 freeze, and I always stress test with it.
EDIT: Though it does appear to be reproducible doing a highly specific test, interesting. Still, I am leaving the above as food for thought...
Here's the other thing though: It STILL would not surprise me if they break BCLK ocing that's become popular while they fix this...
Edit: No BIOS updates since December. I'm sure that doesn't contain a fix...
If it would, I just update the BIOS then.
if this can really be fixed with microcode only, microsoft probably already has a new version of mcupdate_genuineintel.dll available in windows update, *nix users might have to wait for a bios updates (if they ever come)
As to this affecting BCLK OC on non-K CPUs, we'll need to see these BIOSes roll out first, and then the "fixed" BIOS will get the same mod that the current ones do. If it breaks BCLK OC, then you should be able to simply flash back to the appropriate BIOS, and then to avoid the problem, don't mod software, m'kay? :P
besides this looks to me a lot like a marriage of the fdiv and f00f bugs (one only triggered on some situations, the other promptly halted execution until reset), and while people dont run prime95 fft mode with avx acceleration all the time, i still wouldnt want to use a cpu that might trip on some avx usage scenario
However, you are right, it is possible that in the future there will be some software that causes this bug to trigger. Yet by then, these BIOS updates will probably be out.
So, I'd say yes. From what I understand, they are actually disabling FMA3, forcing Prime95 to use the older AVX. That is what is causing the bug, and AFAIK, AMD supports AVX in their processors too(from the FX line on). So it could be something that crops up if you have a program that uses the older AVX. Unless disabling FM3A causes Prime95 to switch to AVX2.0, which AMD doesn't support. In which case you're right, none but a very select few Intel only programs will show an issue.
Y'know? Because stability. Or something.
I'm a bit of a bios modder in my free time.
It appears this issue got fixed with Skylake Microcode update 56 (that's hexidecimal 56), possibly even earlier, I didn't test every version, but patching my bios with that microcode fixed this issue.
Here's the kicker: Microcode update 56 came out 10-24-2015. That's right, almost 3 months ago.
Yep, Intel has had this fixed for a while... Not sure if @btarunr wants to note that or not. ;)
Meanwhile, nearly all skylake boards I played with have old revisions down in the 30-4A range. My gigabyte board I use was particularly low. No idea why the board vendors do this, but they really dropped the ball here.
So blame the board vendors... for not actually using the code intel releases.
I'm skilled enough to patch the microcode on most bioses to the right version if anyone wants to contact me and accept the "if it's bricked it's not my fault" policy etc etc.
Here's a relevant screenshot. Before applying intels proper microcode, this would've crashed long ago: