Dell Latitude 3189 with Pentium N4200 CPU running at 0.79GHz

[DrBeaker]

Hi All,

 

Got a few Dell Latitude 3189 laptops here that have a Pentium N4200 CPU that runs at 1.1GHz stock speed. I've got quite a lot of these devices, most are fine and seem to work as expected.

 

However I've got some of these devices, it seems the CPU never goes above 0.79GHz for whatever reason.

 

* Was the same on a the previous Windows build

* Did a fresh Windows build, Windows 10 x64 1903

* Updated all drivers

* Updated BIOS

* Verified all CPU settings for Boost etc are enabled in the BIOS.

 

All with still the same results - it never goes above 0.79GHz. Initial thoughts were maybe a dodgy Windows install, but it does it on a fresh install of Windows 10 whereas others are fine.

 

Tried the Intel CPU diagnostics tool, doesn't seem to find any issues.

 

They were all bought before I started and I have no history of the devices prior to me starting. So apart from it seeming to be a hardware issue now - I'm out of ideas, any thoughts?

 

Thanks

[Steve21]

You might want to temporarily (only temp! To test once) disable PROCHOT and see if it goes above

 

There’s built in temp warnings that will limit it to 800MHz if it flags above a set level (Same thing will often flag if it’s not a genuine recognised adapter)

 

Steve

[Arthur]

it seems the CPU never goes above 0.79GHz for whatever reason.

I once had an old Dell Latitude laptop do this and it was due to using a third-party AC adapter. After swapping it for a genuine Dell charger, the CPU returned to its normal speed.

[DrBeaker]

You might want to temporarily (only temp! To test once) disable PROCHOT and see if it goes above

 

There’s built in temp warnings that will limit it to 800MHz if it flags above a set level (Same thing will often flag if it’s not a genuine recognised adapter)

 

Steve

 

On these devices it's all-passive cooling, no fan or anything.

 

Whether on battery or mains power it never goes above the 0.79GHz/800MHz barrier. These DO all seem to be from the same batch that were purchased, so I wonder if there's a few duff ones in the batch.

 

My Google-Fu is lacking in finding anything on these, any recalls, advisory notes etc. They were doing the same on the supplied/stock BIOS version that came with the device too.

 

I once had an old Dell Latitude laptop do this and it was due to using a third-party AC adapter. After swapping it for a genuine Dell charger, the CPU returned to its normal speed.

 

Using legit genuine Dell adapters purchased from Dell. I've tried it on a few different but identical laptop PSUs and get the same result. Good point though, I'll try it on some other ones from the trolley itself.

 

 

All the Turbo-boost, C-states, Use all cores settings etc are all enabled in the BIOS. Same settings as one next to it that has the CPU operating normally.

Edited June 23, 2019 by DrBeaker

[Steve21]

On these devices it's all-passive cooling, no fan or anything.

 

The cooling method wouldn't affect if it's throttling it. Even if it's passive if it reached a certain temp it'd flag on.

 

If you try https://www.techpowerup.com/download/techpowerup-throttlestop/ on it does it flag any reasons it's throttling?

 

Steve

[DrBeaker]

Interesting discovery today with these units...

Running on battery power the CPU spikes and starts to behave normally.

Running on mains power it drops down to 0.79GHz and won't budge. Changing the power settings to high performance when on mains and use 100% CPU etc all to no avail. Still stuck at 0.79GHz. Tried another Dell PSU and same result.

 

I would have expected the opposite behaviour. Still seems like a hardware fault IMHO, as the other units I have all behave fine on Mains power with normal CPU usage and never stuck fast as 0.79GHz. Despite Dell's advise to change the size of the page file to a manual size as the fix so far.

[HTCPCP]

This does sound as though there is some form of throttling going on. A couple of things to look at:

1 - Are the batteries fine - this might sound wierd, but i've just had a laptop come in that was running slowly, and the issue was completely caused by a swolen battery. - partly power delivery issues, and partly heat issues caused by batteries and

2 - what are core like when on battery and when on charge? Is there a difference in thermals from it? I tend to use CPUID HWMonitor for this. Might be worth comparing this to one that is working properly?

 

If they are all from the same batch, then it could be a faulty batch of heatpipes, or themal compound, or sensors or motherboard. Either way, good luck getting Dell to admit that it's a problem!

[bald_pig]

The last Dell laptop I used had quite a comprehensive diagnostics utility built in to the BIOS. If the issue appears linked to the power supply it may be worth running the diagnostics to see if it's not pulling enough power from the supply?

 

Also, get one of the seemingly fine laptops and test it with the same power supply for good measure.