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Sorry if this is a noob question (this isn't my normal area) but I need to check something and my Google-fu is failing me.

I have a software build machine (not a VM) running Windows Server 2012 R2 Standard that recently started performing very slowly. (A normal build usually completes in under 30 minutes but was now aborting after 5.5 hours. And the server itself would sometimes momentarily disappear off of the network.) Logging in, I noticed in Task Manager that the CPU (Intel Xeon CPU E5-1410 0 @ 2.8GHz) had a constant speed of 0.14GHz while the utilization bounced between 1-5% (memory was at 20% and there was plenty of free space on the C drive). This situation lasted four days and then improved by itself. It now has a constant speed of 1.18GHz while the utilization occasional peaks to 30%.

My IT guys are from an outsourced company and say the slow down was due to SQL Server on this machine (even though we only use this instance as part of the build process and we stopped all jobs). They say there is nothing wrong.

(a) Does the explanation make sense?

(b) Why doesn't Task Manager (on a non-VM) report the speed at 2.8GHz?

(c) Should I be worried?

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Sounds like dynamic processor speed. Modern processors are able to be dynamically controlled by varying the voltage. This can be controlled in BIOS, or by the operating system. This allows them to generate less heat and use less energy when not using the full power of the processor. It sounds like yours was stuck in a low power state, even though your build process was calling for more processing power.

As for whether to worry, I'd advise that if the phenomena occur again, especially if you can find a way to cause them to happen (can you duplicate the issue?), then you definitely need to troubleshoot deeper. If the phenomenon does not recur, chalk it up to a transient event. Probably a patch that needed application and a restart fixed it.

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Xalorous is correct. Was your CPU usage was high during the time the CPU frequency was at so low? If you are demanding most/all of the CPU for a build, then your frequency should max out (2.8Ghz right?).

This is easy to test. You can run your build, or get a CPU burn in program and watch... if the dynamic frequency scaling isn't working and you don't want to mess around, go into the bios and disable that feature. The name differs from system to system, but I've seen it called Intel Speedstep on Intel platforms.

I don't know how to do it on windows because I'm a generally a Linux guy, but in Linux you can force scaling to be 100% performance all the time via a kernel setting. I'm not sure where the Windows equivalent settings are.

  • Thanks. I logged in and watched a build being performed ... the CPU is now acting as it should. Nevertheless, I've passed on your suggestion to 'my' tech guys so they are aware of this option should the situation occur again at some point. – Peter Trevor Aug 18 '16 at 18:53
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Just had a similar problem after loading Server 2016 from scratch on reformatted RAID drive. Dell R620 box from 2012 with Xeon E5-2670 2.6GHz 1600MHz FSB & 32GB RAM. System previously performed normally with Server 2012 installed. After loading Server 2016, system was excruciatingly slow, Task Manager reported 1% utilization @ 0.16GHz CPU speed.

Long story short: Dell BIOS performance profile of "Performance Per Watt (DAPC-System)" or "Performance" was able to reliably recreate the problem.

Setting the profile to "Performance Per Watt (OS)" cured the problem. System now ranges from 1.2GHz to 3.6GHz depending on system load. This box has a new lease on life!

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