Daniel Hoelbling-Inzko talks about programming

Random PC freezes and reboots under load

Posted by Daniel Hölbling on July 30, 2015

I just switched some components on my computer to get some more speed out of my photography retouching workflow. Since I really hate waiting for Lightroom I opted for a really beefy i7-5820K with a pretty oversized motherboard and plenty of ram. I kept my trusty Geforce GTX 760 TI all of my peripherals - but the 6 (12 logical) cores really ought to speed up my workflow.

So I ordered my stuff and assembled it - even upgraded my case from a Midi-Tower to a Full-Tower to get better air-flow and cooling to my hard drives. I spent way too much time tidying up cables and making the whole build really solid. Everything worked flawlessly at first. Until the next day where I was scheduled for a meeting with a client at 4pm and wanted to transfer some images to the iPad to show during the meeting.

So I spun up Lightroom, selected some of my favourite images from last weeks wedding and hit Export like I did a thousand times before. But this time the computer just rebootet after a few seconds.

Ok so I was royally screwed, I retried immediately and the computer froze once more. Looking into the Eventlog I found a critical Kernel-Power 41 error without any useful description whatsoever.

At that point I had to quit and get to the meeting - without the images, but when I came back and searched a bit online Idiscovered that Kernel-Power 41 can mean a multitude of things, but mostly that the system did not cleanly shut down and that most likely a Power-Supply-Unit issue is causing it.

So I did the math on my components and found that the rig should run at peak power consumption somewhere around 520 Watts - with a bit undersized 550W PSU installed (your PSU should have around 30% headroom over the peak consumption to be able to absorb spikes without any issues). So I frantically searched for a new PSU and got myself a 750W beQuiet! unit. After another hour of routing all the cables and making sure everything is neat and tidy inside my case I turned on the computer - ran a Lightroom export and the system crashed once again :(.

This time I was sure the PSU is fine (and probably has been fine all along) and I looked at the Graphics-Card and the RAM for the culprit. I re-installed everything once more to make sure all the leads are connected correctly and the system still froze.

Next up I decided to reset my UEFI-BIOS to factory defaults and try again - to no avail. Until I decided to disable the Intel XMP RAM overclocking that was being applied and voila - the system is stable under extreme loads! So apparently G.Skill has screwed up somewhere with their G.Skill Ripjaws 4 3000mhz kits and the XMP profile configured by my BIOS was causing system

Turns out: Enabling the XMP Profile for my RAM did not disable the Turbo-Boost. It only overcloed the System to 3.6ghz, but whenever Windows decided the System could use some more Horsepower it instructed the CPU to go into Turbo-Boost which overclocked the overclocked system by another 30%. Needless to say that was outside the safe range for the RAM and the system crashed. I noticed this for the first time after disabling the XMP profile and monitoring my RAM under load - it was already running at 3ghz without the overclock settings in the BIOS.

And: Having your system randomly freeze and reboot at various steps of your Windows updates also sucks - I am now stuck with a failing Windows .NET Framework 4.2 updatee and can't upgrade to Windows 10 :(

Filed under windows, pc
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