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Since I'm running a lot of FEM simulations on my Lenovo W520 laptop, I like to have maximum performance available. Using a nifty tool called ThinkPadFanControl, I'm able to boost my fan speed, so my CPU can run comfortably at >100% for most of the time (up to 2.9GHz on my 2.0GHz Intel i7), limited by 'normal' thermal throttling nicely to stabilize temperatures around 94°C.

However, every now and then, the CPU suddenly throttles back to minimum (8x, so 0.78GHz) for up to ten minutes. HWiNFO64 reports thermal throttling as No for all cores during those minutes; temperatures will fall well below 80°C, and all other temperatures (SMART, GPU, memory) seem to be fine as well. Performance becomes very sluggish, with visible delays in typing, switching between applications, etc.

Is this known behaviour in Intel Core i7 processors? How can I prevent or mitigate this?

In the meantime, I have updated my BIOS; I have disabled SpeedStepping so that the frequency remains below 2.0GHz, to no avail. However, I have also noticed some issues with my charger; perhaps a broken connection is causing the laptop to revert to battery saving mode, despite being connected to a charger.

Edit: It turned out the thermal paste was completely solidified, causing erratic behaviour - I suppose I hit some protection that is a bit more stringent than just the thermal throttling, so I was looking in the wrong direction. All is well now with new cooling paste; flagged the question as a duplicate.

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  • Your laptop shouldn't be getting that hot, even if you are running it 24/7, at 100% usage. The fact its throttling back to 0.78GHz indicates a thermal problem which you should resolve. "Is this known behaviour in Intel Core i7 processors?" - Yes; Intel designs their processors to automatically scale their frequency down in order to prevent thermal damage. "How can I prevent or mitigate this?" - Depending on your hardware you might be able to disable this protection, but that would result in, a hard crash because the most extreme protections can't be turned off.
    – Ramhound
    Jan 20, 2017 at 13:55
  • @Ramhound Then why is the temperature indicated to be well below 80 quickly after this happens, with thermal throttling reported to be off? Is this a thermal protection beyond what the processor reports as throttling?
    – Sanchises
    Jan 20, 2017 at 14:06
  • I would argue that, it's well below 80, because it happened.
    – Ramhound
    Jan 20, 2017 at 14:29
  • @Ramhound I'm not sure I'm following you. The problem is that, even when the laptop has cooled down sufficiently, it still keeps the CPU throttled back to minimum.
    – Sanchises
    Jan 24, 2017 at 9:51
  • @Sanchises - There is delta between, the reported temperatures reported by the sensor, and the actual temperatures of the CPU die itself.
    – Ramhound
    Feb 3, 2017 at 13:45

1 Answer 1

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Is the Lenovo W520 from around the 2011 era? what version is the BIOS?

I ask because I noted a cpu throttling problem that seemed independent of temp with the Lenovo x220 that was fixed with a bios update in 2011..here http://vivithemage.com/2011/09/08/lenovo-x220-bios-1-21-fixes-cpu-throttling-problem/

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  • I updated my BIOS before asking this question, to no avail. But it is indeed from 2011.
    – Sanchises
    Jan 24, 2017 at 9:43
  • Try going into the BIOS and find something called CPU Power Management or Intel SpeedStep and disable it. And see if you get the same problem. There is package power management in addition to thermal management. There may be firmware bugs or something. Also, download HWiNFO64 (or 32) and click on the Sensors tab. that will show you thermal and package power management and whether it's being throttled due to package power. Jan 25, 2017 at 18:27
  • Also, does your battery still charge? i.e. does the laptop work if not plugged in? I'm assuming you're plugged in above. I note Lenovo had a firmware update for their battery. Wondering if maybe your battery is reporting it can't charge support.lenovo.com/us/en/downloads/ds001322 Jan 25, 2017 at 18:36
  • I disabled Intel SpeedStep to no avail. Also, from my question, "HWiNFO64 reports thermal throttling as No". Battery reports everything working fine.
    – Sanchises
    Jan 25, 2017 at 19:14
  • hmm. enigma. I'm still guessing a firmware issue. What bios version do you have? Also, there's an ECP (Embedded Control Program). Did you update with this support.lenovo.com/us/en/downloads/ds018884 UEFI BIOS ECP Release 1.43 (8BET63WW) 1.36 (8AHT42WW) Jan 26, 2017 at 4:56

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