How to detect thermal throtteling?

I have a Dell XPS 15 Laptop, i7-2720QM CPU, 2.20 GHz, Win 8.1 which currently slowed down significantly. Fan goes on quite often.

I have checked the following:

sufficient free disk space > 10 GB
no significant new software installed.
So suspicious entries in System log.

Therefore I suspect it is an thermal throtteling issue. Before changeing/cleaning the fan which requires quite a lot of screws to open at the XPS15 I want to confirm this suspect more. I have tried out several tool get more evidence on this. Max CPU temperature is mostly around 78 °C, at low load opertion ~ 55 °C. (Example screenshot below)

Anyhow I couln't find a tool which, directly showed me if CPU throtteling is currently active. (Or I at least I couldn't identify the parameter indicating this)

Questions:

With which tool i can see directly if thermal throtteling is activated?
At which parameter shall I look?

Edit:

Some more observations: AT full load I reach temperature upto 90 °C. The cpu speed (measured with Prime64 & CPU-Z) stays almost constant at 2.2 Ghz, while it seems to allow overboosting with 3 GHz at low load). I additionally found out that CPU-Z displays the factor `Multipier' in the range of 22 .. 24, whilest this factor is 33 at low load. Is this factor a additional measure for thermal throtteling? What is the expected value without throtteling (is it 33)?

BerndGit

Posted 2016-11-09T10:17:09.423

Reputation: 157

So you are over 30 degrees from the thermal max of your hardware. 70 degrees at max load is normal for the hardware you have. Its a laptop, most laptops, have really bad cooling. "which currently slowed down significantly." - Describe this problem in more detail. CPU-Z is reporting your CPU is actuallying allowing itself to be boosted, since it's frequency, is faster then its base clock. – Ramhound – 2016-11-09T15:18:21.180

Answers

In order to find out whether your CPU is actually throttling, you should be able to use Intel's Extreme Tuning Utility (XTU). I run it on my Ivy Bridge (3rd Gen) systems, but it should work the same on your Sandy Bridge (2nd Gen) CPU.

The Extreme Tuning Utility can directly indicate whether the CPU is throttling or not (see screenshot), and it is also a very convenient tool for observing other information such as CPU utilization, temperatures and frequencies.

Nassbirne

Posted 2016-11-09T10:17:09.423

Reputation: 1 049

I don't quite understand it.. before it was showing yellow (i.e. throttling).. now it doesn't (I'm not quite stressing it as much - but still stressing it) and although it never goes yellow (i.e. is a solid blue "no"), it still keeps jumping my max core frequency around way below base (3ghz) but it cycles between 2 and 3.68.. so if it is doing that is it still throttling even though it is not reported as such? I'm A/C – Mikey – 2018-01-16T14:05:37.500

Prime95 can show you the exact CPU speed, but you don't need any tools to confirm that. It is obvious that your CPU is overheating. Stop the server, make sure the fans are working and apply new thermal paste on the dies.

The CPU temperature at full load should not exceed 60°C. You are significantly over the limit.

Overmind

Posted 2016-11-09T10:17:09.423

Reputation: 8 562

Thanks for the hint. I got prime95 from http://www.mersenne.org/. CPU temp now up to 92°C. Where exactly do I see the actual CPU speed? (btw.: It is a laptop not a server. Here the exchange/cleaning of the fan is singifiacntly more difficult)

– BerndGit – 2016-11-09T10:45:55.387

Options-->CPU. Well, you have to do it even if it's difficult. Or get a tech guy to do that, you just tell him what's needed. – Overmind – 2016-11-09T12:05:49.823

I wouldn't care about possible throttling, indeed your laptop gets too hot. Try blowing pressurised air into the fan outlet. This can result in significantly lower temperature. You won't get it much cleaner by opening it. If the fan runs smoothly (you can hear that), it is most probably the cooling paste that isn't good anymore. It depends a lot on your specific laptop model how much work it is. On my thinkpad it's doable within 1 hour (probably 2-3 hours if you haven't done it before and are very careful). – BramMooij – 2016-11-09T14:10:23.397

Look at this video to see how to disassemble your laptop (should be the right model I think), if this frightens you, ask someone who has experience or contact a Tech. If it doesn't try it yourself. Most of it is just taking screws out, and it's usually not too difficult. It does take quite some time to figure out how to unclip things and make sure you don't mess anything up. I always use small glasses for the screws. Use a different glass for every stage of disassembly, such that you know which screw came from where. – BramMooij – 2016-11-09T14:15:14.773

Thanks for thath comment. Yes I have seen videos and Dell service manuals on how to exchange fan. In fact I have done some service on this laptop already on my own (exchange Keyboard and HDD). Anyhow before starting this operation I would like to have more confirmation that insufficient cooling is realy the root cause. Therefore my question here at SU. – BerndGit – 2016-11-09T15:40:56.533

Seems that we have some overboosting at low them upto 3 GHz, and 2.2 Ghz at high load. More in my edit above. – BerndGit – 2016-11-09T15:54:55.960