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MonkeyBurrito
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Registered: ‎10-22-2018
Location: US
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Message 1 of 16

X1 Carbon Gen 6 CPU Throttling - CPU Speed is Capped

Hello everyone,

 

I recently bought a thinkpad x1 carbon 6th gen. I'm experiencing severe CPU throttling.

My model number is 20KH002KUS

 

My main probelm is that during benchmarks, my CPU clock speed stays at 1.5ghz while on battery. On AC power, the CPU speed is capped at around 2.4ghz, still not what this machine is capable of. I am getting terrible benchmark scores. I have tried all sorts of "fixes," nothing worked. My BIOS version is 1.31, the latest update. 

 

What can I do? I may have a deffective unit, if so I will return to Lenovo. However I believe there is a way to solve this, with some settings in the BIOS maybe, or maybe there is a problem with this BIOS version.

 

Please help, thank you.

 

bytemaster1
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Message 2 of 16

Re: X1 Carbon Gen 6 CPU Throttling - CPU Speed is Capped

Speaking from the perspective of an X1Y3, which is basically the same machine, I can tell you that BIOS settings make a big difference. As does Windows settings:

 

1. In BIOS, make sure that under battery mode, you have it set to optimize battery, and maximum performance for AC. When on battery, your CPU will thermal throttle rather than spin up the fans. This saves lots of battery, and keeps the machine pretty cool. It does cause aggressive throttling, but it actually ends up being a benefit in the long run. When on AC, you'll definitely see CPU speeds bump up pretty quickly.

2. Make sure you have your power settings set to Balanced or Performance (but NOT maximum performance) for AC and Battery respectively. If you set to maximum performance, under AC power, it will peg your clocks to maximum. This will cause fast thermal throttling. That's right. You'll get better performance under balanced than you will under maximum performance, because the CPU package says cooler overall.

 

So, check BIOS, and check Windows power settings, and let us know how it works.

MonkeyBurrito
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Message 3 of 16

Re: X1 Carbon Gen 6 CPU Throttling - CPU Speed is Capped

1. The BIOS settings were on balance by default, I set them to max performance and I was still getting the same throttling.
2. Under windows power settings there is no option to change my power plan. The only available option is "balanced"

I'm sorry if I haven't mentioned this, but I've tried almost everything you can possibly think of. I've went through so many forum posts and reddit threads, that I finally decided to create my own post on the lenovo forums.
bytemaster1
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Message 4 of 16

Re: X1 Carbon Gen 6 CPU Throttling - CPU Speed is Capped

So, battery mode should be "battery optimized" or "balanced" and AC should be "maximum performance." I realize you've checked that. However, in Windows, I'm actually talking about the slider that appears if you click on the battery icon. Make sure it's not all the way to the right, as this will cause nearly immediate thermal throttling. If that still doesn't do it, your heat sink may not have enough thermal compound. Not sure if that's actually the case, but I suppose it's possible.
MonkeyBurrito
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Message 5 of 16

Re: X1 Carbon Gen 6 CPU Throttling - CPU Speed is Capped

Alright I did not know this slider exists. Its was "better performance" the second bar from the right. I will set to "better battery" and see what the results are. 

MonkeyBurrito
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Message 6 of 16

Re: X1 Carbon Gen 6 CPU Throttling - CPU Speed is Capped

Update: after setting the slider to "better battery" I am still experiencing the same issue. Clock speed is still capped at 1.5ghz and benchmark scores are absurdly low.
bytemaster1
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Message 7 of 16

Re: X1 Carbon Gen 6 CPU Throttling - CPU Speed is Capped

"Better performance" should have been okay. As long as it's not "maximum performance." Does your fan come on at all?
MonkeyBurrito
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Message 8 of 16

Re: X1 Carbon Gen 6 CPU Throttling - CPU Speed is Capped

The fan comes on only when plugged into power.
bytemaster1
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Message 9 of 16

Re: X1 Carbon Gen 6 CPU Throttling - CPU Speed is Capped

When on battery, I rarely see CPU speeds bump up beyond 2.4GHz. Generally it stays in the 1.5s or so. That's normal for battery. When you're on AC, download HWMonitor (https://www.cpuid.com/), and leave it open as you do various tasks. I bet you see it bumping up to 4.2GHz max, while it mostly hovers around 1.2-1.8GHz when idle.  Are you running the 8650U? If so, I'd be happy to run the same benchmark and see what I get.

 

Also, keep in mind that these machines are rated for 15W TDP, but that the CPU can hit 25-30W TDP when spooling up to turbo frequencies. There's no way you'll get the CPU to peg at 4.2GHz non-stop at load. And, these (and all) machines suffer from heat soak, which worsens the more you bench it. Run HWMonitor and see what it says for your max fequencies.

MonkeyBurrito
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Message 10 of 16

Re: X1 Carbon Gen 6 CPU Throttling - CPU Speed is Capped

Yes, mine is the i7 8650U.
I do see some of the cores jump to 3.5 to to 4ghz occasionally, when just using chrome.
On battery it stays at 798mhz and jumps up much less often.

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