Subject: Processors | June 26, 2017 - 08:53 AM | Sebastian Peak
Tagged: xeon, Skylake, processor, pentium, microcode, kaby lake, Intel, errata, cpu, Core, 7th generation, 6th generation
A microcode bug affecting Intel Skylake and Kaby Lake processors with Hyper-Threading has been discovered by Debian developers (who describe it as "broken hyper-threading"), a month after this issue was detailed by Intel in errata updates back in May. The bug can cause the system to behave 'unpredictably' in certain situations.
"Under complex micro-architectural conditions, short loops of less than 64 instructions that use AH, BH, CH or DH registers as well as their corresponding wider register (eg RAX, EAX or AX for AH) may cause unpredictable system behaviour. This can only happen when both logical processors on the same physical processor are active."
Until motherboard vendors begin to address the bug with BIOS updates the only way to prevent the possibility of this microcode error is to disable HyperThreading. From the report at The Register (source):
"The Debian advisory says affected users need to disable hyper-threading 'immediately' in their BIOS or UEFI settings, because the processors can 'dangerously misbehave when hyper-threading is enabled.' Symptoms can include 'application and system misbehaviour, data corruption, and data loss'."
The affected models are 6th and 7th-gen Intel processors with HyperThreading, which include Core CPUs as well as some Pentiums, and Xeon v5 and v6 processors.
Subject: Processors | December 4, 2015 - 11:35 PM | Sebastian Peak
Tagged: Skylake, Intel, heatsink, damage, cpu cooler, Core i7 6700K, Core i7 6600K, bend, 6th generation, 3rd party
Some Intel 6th-gen "Skylake" processors have been damaged by the heatsink mounts of 3rd-party CPU coolers according to a report that began with pcgameshardware.de and has since made its rounds throughout PC hardware media (including the sourced Ars Technica article).
The highly-referenced pcgameshardware.de image of a bent Skylake CPU
The problem is easy enough to explain, as Skylake has a notably thinner construction compared to earlier generations of Intel CPUs, and if enough pressure is exerted against these new processors the green substrate can bend, causing damage not only to the CPU but the pins in the LGA 1151 socket as well.
The only way to prevent the possibility of a bend is avoid overtightening the heatsink, but considering most compatible coolers on the market were designed for Haswell and earlier generations of Intel CPU this leaves users to guess what pressure might be adequate without potentially bending the CPU.
Intel has commented on the issue:
"The design specifications and guidelines for the 6th Gen Intel Core processor using the LGA 1151 socket are unchanged from previous generations and are available for partners and 3rd party manufacturers. Intel can’t comment on 3rdparty designs or their adherence to the recommended design specifications. For questions about a specific cooling product we must defer to the manufacturer."
It's worth noting that while Intel states that their "guidelines for the 6th Gen Intel Core processor using the LGA 1151 socket are unchanged from previous generations", it is specifically a change in substrate thickness that has caused the concerns. The problem is not limited to any specific brands, but certainly will be more of an issue for heatsink mounts that can exert a tremendous amount of pressure.
An LGA socket damaged from a bent Skylake CPU (credit: pcgameshardware)
From the Ars report:
"Noctua, EK Water Blocks, Scythe, Arctic, Thermaltake, and Thermalright, commenting to Games Hardware about the issue, suggested that damage from overly high mounting pressure is most likely to occur during shipping or relocation of a system. Some are recommending that the CPU cooler be removed altogether before a system is shipped."
Scythe has been the first vendor to offer a solution to the issue, releasing this statement on their support website:
"Japanese cooling expert Scythe announces a change of the mounting system for Skylake / Socket 1151 on several coolers of its portfolio. All coolers are compatible with Skylake sockets in general, but bear the possibility of damage to CPU and motherboard in some cases where the PC is exposed to strong shocks (e.g. during shipping or relocation).This problem particularly involves only coolers which will mounted with the H.P.M.S. mounting system. To prevent this, the mounting pressure has been reduced by an adjustment of the screw set. Of course, Scythe is going to ship a the new set of screws to every customer completely free of charge! To apply for the free screw set, please send your request via e-mail to firstname.lastname@example.org or use the contact form on our website."
The thickness of Skylake (left) compared to Haswell (right) (credit: pcgameshardware)
As owner of an Intel Skylake i5-6600K, which I have been testing with an assortment of CPU coolers for upcoming reviews, I can report that my processor appears to be free of any obvious damage. I am particularly careful about pressure when attaching a heatsink, but there have been a couple (including the above mentioned Scythe HPMS mounting system) that could easily have been tightened far beyond what was needed for a proper connection.
We will continue to monitor this situation and update as more vendors offer their response to the issue.
Skylake Architecture Comes Through
When Intel finally revealed the details surrounding it's latest Skylake architecture design back in August at IDF, we learned for the first time about a new technology called Intel Speed Shift. A feature that moves some of the control of CPU clock speed and ramp up away from the operating system and into hardware gives more control to the processor itself, making it less dependent on Windows (and presumably in the future, other operating systems). This allows the clock speed of a Skylake processor to get higher, faster, allowing for better user responsiveness.
It's pretty clear that Intel is targeting this feature addition for tablets and 2-in-1s where the finger/pen to screen interaction is highly reliant on immediate performance to enable improved user experiences. It has long been known that one of the biggest performance deltas between iOS from Apple and Android from Google centers on the ability for the machine to FEEL faster when doing direct interaction, regardless of how fast the background rendering of an application or web browser actually is. Intel has been on a quest to fix this problem for Android for some time, where it has the ability to influence software development, and now they are bringing that emphasis to Windows 10.
With the most recent Windows 10 update, to build v10586, Intel Speed Shift has finally been enabled for Skylake users. And since you cannot disable the feature once it's installed, this is the one and only time we'll be able to measure performance in our test systems. So let's see if Intel's claims of improved user experiences stand up to our scrutiny.
That is a lotta SKUs!
The slow, gradual release of information about Intel's Skylake-based product portfolio continues forward. We have already tested and benchmarked the desktop variant flagship Core i7-6700K processor and also have a better understanding of the microarchitectural changes the new design brings forth. But today Intel's 6th Generation Core processors get a major reveal, with all the mobile and desktop CPU variants from 4.5 watts up to 91 watts, getting detailed specifications. Not only that, but it also marks the first day that vendors can announce and begin selling Skylake-based notebooks and systems!
All indications are that vendors like Dell, Lenovo and ASUS are still some weeks away from having any product available, but expect to see your feeds and favorite tech sites flooded with new product announcements. And of course with a new Apple event coming up soon...there should be Skylake in the new MacBooks this month.
Since I have already talked about the architecture and the performance changes from Haswell/Broadwell to Skylake in our 6700K story, today's release is just a bucket of specifications and information surround 46 different 6th Generation Skylake processors.
Intel's 6th Generation Core Processors
At Intel's Developer Forum in August, the media learned quite a bit about the new 6th Generation Core processor family including Intel's stance on how Skylake changes the mobile landscape.
Skylake is being broken up into 4 different line of Intel processors: S-series for desktop DIY users, H-series for mobile gaming machines, U-series for your everyday Ultrabooks and all-in-ones, Y-series for tablets and 2-in-1 detachables. (Side note: Intel does not reference an "Ultrabook" anymore. Huh.)
As you would expect, Intel has some impressive gains to claim with the new 6th Generation processor. However, it is important to put them in context. All of the claims above, including 2.5x performance, 30x graphics improvement and 3x longer battery life, are comparing Skylake-based products to CPUs from 5 years ago. Specifically, Intel is comparing the new Core i5-6200U (a 15 watt part) against the Core i5-520UM (an 18 watt part) from mid-2010.