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liakify
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Posts: 5
Registered: ‎04-05-2018
Location: SG
Views: 3,762
Message 1 of 17

CPU performance & heating issues (ideapad 720s 14IKB 81BD)

I got this laptop in Jan this year, and basically it's been great except for some strange CPU behaviour which I need answers for...

Mine has the following configuration: i7-8550u / 16gb RAM / 512gb PCIe SSD / MX150

 

Situation

Out of the box, when under heavy load / doing stress tests the CPU refuses to go beyond 2ghz on all 4 cores. But in regular use clock speeds on all 4 cores do spike to almost 4ghz sometimes. Basically it seemed quite glaring to me that the CPU wasn't performing as well as it is capable of. Turbo boost was acting strangely.

 

My investigations

Tried using throttlestop to fiddle with settings and it looked like turbo boost wasn't fully enabled by default. Throttlestop enabled me to let turbo boost run indefinitely without the 2ghz cap. However over time I noticed that my CPU easily rose to temps beyond 80C (in short bursts) even in regular use. This was with the default TDP limit configured to be 18.75W. So in order to test the system's cooling performance, I did a CPU & GPU stress test at the same time using XTU & Furmark and CPU temps went into the high 90s and caused my system to crash. Same thing happened even after I lowered the TDP to 15W. All of this happened despite undervolting the CPU

 

For context ambient temps here are usually ~30C, and regular use temps are perfectly fine at ~40-50C (excluding the above).

 

So now fearing that longevity might be affected cause of consistent heat spikes I have reset all settings and removed throttlestop. System still remains undervolted in XTU though. When doing combined CPU & GPU stress tests with the CPU capped at 2ghz the temps are still ok at ~80C. By staring at hwinfo, I discovered that turbo boost actually turns on and off randomly which is why sometimes it can boost really high but other times it just caps at 2ghz. I also noticed in hwinfo that SpeedShift is disabled by default. I do want to have SpeedShift enabled, but I can't do it in the BIOS and I don't want to use throttlestop cause it can fry my computer. 

 

Questions

1. Anyone else with this same laptop having thermal issues or is it just me?

2. Is the CPU enabling and disabling turbo randomly because of the laptop's thermal design?

3. Is there a way to enable SpeedShift without using throttlestop?

 

TL;DR

CPU enables and disables turbo boost on its own randomly. But when enabling turbo boost computer has tendency to reach high temps under normal use. 

及時雨
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Registered: ‎02-25-2018
Location: TW
Views: 3,655
Message 2 of 17

Re: CPU performance & heating issues (ideapad 720s 14IKB 81BD)

Hi!

My 720s is also 14IKB-81BD with i5-8250u with 16GB RAM / 256G SSD

 

The situation I encounter is similar to yours.

I have upgrade BIOS to V1.06 recently.

After upgradation I found my turbo boost clock is locked at "1.8"Ghz,

which means my cpu clock never higher than 1.8 Ghz.

 

I went to surf the net and found "throttlestop".

Through this software I found the speed shift is default "off".

Whenever I turned speed shift on manually, the cpu clock is soon boosted.

But the boost configuration also needs to be defined manually; if not,

my cpu get burning to higher temperature.

 

I think this is a BIOS issue. So I am considering to report this.

 

 

Wutikorn
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Registered: ‎06-16-2016
Location: US
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Message 3 of 17

Re: CPU performance & heating issues (ideapad 720s 14IKB 81BD)

Did you report this problem?  I have this problem too.  Also, Intel Speedshift Technology (SST) is disabled, and no option to enable it.  Lenovo should add this to it BIOS.  I contacted support in my country, but I don't think they forward anything to the developer team.

ext73
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Posts: 25
Registered: ‎08-17-2018
Location: PL
Views: 2,372
Message 4 of 17

Re: CPU performance & heating issues (ideapad 720s 14IKB 81BD)

kor1
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Posts: 10
Registered: ‎08-18-2018
Location: DE
Views: 2,324
Message 5 of 17

Re: CPU performance & heating issues (ideapad 720s 14IKB 81BD)

Can't install new bios version. Any ideas why?

liakify
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Registered: ‎04-05-2018
Location: SG
Views: 2,306
Message 6 of 17

Re: CPU performance & heating issues (ideapad 720s 14IKB 81BD)

I got the same error message trying to go from bios 1.06 to 1.08, strange...but from the description it seems to merely be a security patch (Intel and OEMs probably in a mess ever since meltdown and spectre)

 

On a side note there was a chipset update I found that was related to cpu temp and performance management. Haven't properly tested it, but from what I've observed it didn't seem to change the original weird behavior of turbo switching on and off randomly, and speed shift is still off. 

ext73
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Posts: 25
Registered: ‎08-17-2018
Location: PL
Views: 2,183
Message 7 of 17

Re: CPU performance & heating issues (ideapad 720s 14IKB 81BD)

Regarding the Turbo Boost issue under the BIOS 1.06. If you use Linux, I recommend to build and install thermald 1.8 dev ... for example, under my kernels for Ubuntu [www.netext73.pl] you will easily get a Turbo ... but its 'boundaries' are scandalous ... Lenovo Who sets you up these rules ?!?!Screenshot_20180822_153029.pngScreenshot_20180822_153341.png

kor1
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Registered: ‎08-18-2018
Location: DE
Views: 2,147
Message 8 of 17

Re: CPU performance & heating issues (ideapad 720s 14IKB 81BD)

CPU just works fine with the help of ThrottleStop. Lenovo sells an i7 which is slower than an i5 out of the box. It's a shame Smiley Sad
ext73
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Posts: 25
Registered: ‎08-17-2018
Location: PL
Views: 2,122
Message 9 of 17

Re: CPU performance & heating issues (ideapad 720s 14IKB 81BD)

There is an evident BIOS problem here ... which can be seen in the fact that sometimes it either generates errors or not. As for me, they deliberately excluded Turbo Boost = breached the terms of the contract with the customer - further misleading - in the description of bios 1.06 there was NO WORDS about blocking one of the most important processor features ... and from time to time we can manages to overwrite the bios these conditions.Screenshot_20180823_094941.png

kor1
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Registered: ‎08-18-2018
Location: DE
Views: 2,112
Message 10 of 17

Re: CPU performance & heating issues (ideapad 720s 14IKB 81BD)

Isn't it possible to build a mod bios which performs well and let the CPU work like it should? Is anybody able to do that?

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