Thank you for contacting Intel Communities.
In regards to your question "What is the maximum core frequency for this CPU when all cores are utilized?"
You can click here to check the maximum frequencies while the Intel® Turbo Boost Technology is enabled, please expand 4th Generation Intel® Core™ i5 Desktop Processors and look for the processor you have.
You can disable the Intel® Turbo Boost Technology from the BIOS (if the option is available).
In regards to the issue with Prime95 and the Skylake (6th gen) processors, it is not related to any other families of processors.
For troubleshooting purposes, you can test the system in a Windows environment to run the Intel® Processor Diagnostic Tool as the Linux* version is available for Fedora only and won't necessarily run in Debian, you can download the tool here.
You can also test the processor in a compatible motherboard to see if the problem persists.
If you tested the RAM modules using Memtest86 or any other memory testing tool I would recommend testing with different sticks of RAM.
Please let me know how it goes.
First of all, thank you for giving some hints and advises. The issue is still under investigation, but there's some progress:
- Intel Processor Diagnostic Tool gives me "pass" on each run
- Core clocks looks normal, according to Turbo Boost Technology Matrix. If all 4 cores are fully utilized, each are running at 2.6 GHz.
- System is stable even under high load. The only workload which triggers the issue (so far) is running x264 video encoder. Based on my tests, it's unpredictable when it's causing freeze. Sometimes it takes only a few seconds, another time just after about 15 minutes.
- I did some tests on my desktop PC (Z97 chipset, Xeon E3-1240 v3, 2x8GB DDR3 modules), with the same workload (same OS, kernel, application, test video file) but unable to reproduce the issue.
Since I still suspect the CPU or the mainboard, the plan is to swap the CPUs and repeat the tests on both system.
After many hours of testing, here are the results.
PC #1: ASRock Z97M-ITX/AC, BIOS v1.80 (6/29/2016), 2x4GB DDR3-1600 (Kingston HyperX Blue), no add-on VGA
PC #2: ASRock Z87 Extreme4, BIOS v3,40 (4/28/2016), 2x8GB DDR3-1600 (Kingston HyperX Blue), NVIDIA GTX1080
System CPU Turbo Boost Operating system Duration Workload Result PC #1 Core i5-4590T Enabled Debian, Linux 4.9.13 1-15 min x264 Freezing PC #1 Core i5-4590T Enabled Debian, Linux 4.9.13 5+ days Apache httpd, Tomcat, MySQL, Samba, QEMU-KVM Stable PC #1 Core i5-4590T Enabled Debian, Linux 4.4.39 1-15 min x264 Freezing PC #1 Core i5-4590T Disabled Debian, Linux 4.9.13 1-15 min x264 Freezing PC #1 Core i5-4590T Enabled Windows 10 Pro x64 120+ min x264, AIDA64 Stress test, Intel PDT Stable PC #1 Pentium G3240T N/A Debian, Linux 4.9.13 60+ min x264 Stable PC #1 Xeon E3-1240 v3 Enabled Debian, Linux 4.9.13 60+ min x264 Stable PC #2 Xeon E3-1240 v3 Enabled Windows 10 Pro x64 120+ min Generic desktop usage (Office, gaming, etc.) Stable PC #2 Xeon E3-1240 v3 Enabled Windows 10 Pro x64 60+ min x264, AIDA64 Stress test, Intel PDT Stable PC #2 Core i5-4590T Enabled Debian, Linux 4.9.13 1-15 min x264 Freezing PC #2 Core i5-4590T Disabled Debian, Linux 4.9.13 1-15 min x264 Freezing
- i5-4590T is freezing under Linux, regardless Turbo Boost state and mainboard
- PC #1 is stable under Linux with Pentium G3240T and Xeon E3-1240 v3 under the workload where 4590T is freezing
- PC #1 is stable under Windows 10 with i5-4590T
- Windows port of x264 is slower under Windows, however it reports to use the same CPU instruction kits
- CPUID of Xeon E3-1240 v3 and i5-4590T is the same (306C3)
- BIOS of PC #1 and #2 contains the same microcode update revision which is 19
- Windows 10 Pro applies microcode update rev 1E (8/13/2015)
- Debian applies microcode update rev 20 (3/16/2016), however system behaves similarly without OS-based microcode update
- Checking and comparing "Specification Update" documents for Xeon E3-1200 v3 and Desktop 4th Generation Core processor family
- Trying to apply microcode update rev 1E under Linux
- Re-ccompile x264 binary under Linux and repeat tests in PC #1 with i5-4590T
Any comments and suggestions are welcome. I'm open to any idea what to check.
Thank you for the information.
Seems that the recommendation about testing the system in a Windows environment worked:
PC #1 Core i5-4590T Enabled Windows 10 Pro x64 120+ min x264, AIDA64 Stress test, Intel PDT Stable
This is because our drivers are fully supported while using Windows 7, 8 or 10*, on the other hand, while using a different OS, you may encounter different issues.
What drivers do you mean? HD graphics driver for Linux-based systems, or something else? I know that the best support by most of the hardware vendors is given for Windows, but did you mean that Intel does not officially support 4th Generation Core i5 under Linux? Info of the kernel module says that the driver is created by Intel:
license: GPL and additional rights
description: Intel Graphics
author: Intel Corporation
author: Tungsten Graphics, Inc.
Anyway, back to the original topic. Since Xeon E3-1200 v3 series and 4th Gen Core i5 are built upon the same microarchitecture (even the CPUID signature and microcode update is the same), I would say they should behave similarly under the same workload. However the fact is that Xeon is working perfectly, but i5 is failing. Let's forget the obvious performance differences (core frequency, cache size) for a while, and let's focus on the differences based on the public info found on ark.intel.com:
- Vertical segment (desktop vs server) -> should not be an issue, if Linux support is the same for both
- Hyperthreading -> Xeon is stable with disabled HT
- TDP -> should not be an issue
- ECC memory support -> no ECC memory is used in any of my PCs
- Integrated graphics -> PC #2 has a PCIe graphics adapter and i5 is also failing in that configuration
- TSX-NI -> as I know, this feature is disabled on Xeon because of a faulty implementation
It looks like the major difference is the integrated graphics controller: E3-1240 v3 does not have it. Maybe HD Graphics controller is causing the trouble even if an external VGA is used? Errata section of Specification Update released for Desktop 4th Generation Intel Core Professor Family mentions issues, like:
- HSD77 - Graphics Processor Ration And C-State Transitions May Cause a System Hang
- HSD139 - Concurrent Core and Graphics Operation at Turbo Rations May Lead to System Hang
How can I check if my CPU is affected or not?
I tried loading different microcode updates on i5-4590T, but no change.
You are correct, I meant graphics drivers, for Linux users, the support is provided through the distros' community.
Based on the tests you did, you got issues in both situations (with Turbo Boost enabled and disabled). Regarding the configuration in question (with the Intel® Core™ i5-4590T Processor), the system worked while using Windows® 10, then, at this point, we can't blame the Intel® Turbo Boost Technology.
In regards to the Errata, I can do further research and then get back to you.
I agree and convinced that the issue is not related to Turbo Boost Technology, but still curious what is the root cause of these freezes. I appreciate your efforst on checking Errata, maybe you'll find a clue why a CPU is affected and another from the same generation doesn't.
Thanks again in advance!