Dell Inspiron 7000 2-in-1 (7348, i7-5500u): Sub-optimal clock speed under load.

Hi,

I have a clock speed issue with my i7-5500u. Its base clock is (according to Intel) rated at 2.4GHz, a multiplier of 24. However, when I was testing out the stability of the system (both thermal and arithmetic), I noticed that CPU doesn't stay at its rated base clock of 2.4GHz. Instead, it fluctuates between a multiplier of 22 and 23, giving only 2.2-2.3GHz. I've tested this on 5 different 7348 units, of which, two are solid at 2.4GHz, but three are below 2.4GHz.

Additional details:
BIOS: A01
Windows updates: Up to date as of 6th March 2015
Ambient temperature: Approx 20-21 c
Full load CPU temperature: 68-70 c
Internal cooling fan RPM: 6950-7000
Full load applications used (one at a time): LinX, Intel Linpack (problem size of 23118, or 4096MB)
Clock speed information applications used: Open Hardware Monitor, CPU-Z
Power profile: High performance
Power source: AC Power

Could any of the Inspiron 7348 user test their systems and see what behaviour you're getting?

 

Hi,
I checked mine, and its fine (jumping between 23 to 24 and even 25 sometimes)
btw bios version A03 is available and you can download it here:
http://www.dell.com/support/home/il/en/ildhs1/Drivers/DriversDetails?driverId=30THK

I have fan noise issue:

Dell's lab says that it is normal.
are your units loud as well?

 

I ran the same test (LinX) on this year's XPS 13 with an i5-5200u. That system was clocking in with the same performance (GFLOPS) as the i7-5500u from the 7348. Throughout the test period on the XPS 13, its clock speed stayed solid on 2.2GHz (the rated base clock of a 5200u from Intel).

So, I'm scratching my head on why the i7-5500u from the 7348 is under-performing.

 

I'll give the A03 BIOS a try, thank you.

(Really appreciate the link. For some reason, when I enter my service tag to the download site, it was only showing me the A01 BIOS.)

 

I'm uploading a test video to Youtube now. How did you get Dell to respond to your video?

 

Looks like it's a clockspeed throttling issue. Temperature stays constant at 70c, but the clockspeed is lowered/controlled.

 

I posted it on some video of their,
Is i5 5200u really out perform i7 5500u?

 

I tested it with prime95 and cpuz.
My system is currently updating, I will test it with Linx after it done.
Your system sound much quiter then mine.
Thanks for the upload

 

I tested both the demo unit of XPS 13 (2015 model) and the demo unit of the Inspiron 7348 at a local Microsoft store. Using the linpack included in the LinX 0.6.5 (this is an older linpack than the current one from Intel's website, i.e. not optimized for the latest processors. But used here to give a relative/comparative performance measure), the i5-5200u on the XPS13 was giving 48GFLOPS, same as the i7-5500u on the Inspiron.

It appears as if the system (Inspiron 7348) is holding back the processor.

Dell, if you're reading this: Please don't hold back the processor because you've now created a system that only has a base clock of 2.2GHz (in my case). The system should be capable of dissipate the total amount of heat generated by the 15W TDP processor (i7-5500u, in this case), without having to resort to performance throttling.

 

Speedfan (checked the "Enabled DELL support" option, from Readings tab --> Configure --> Options tab) tells me the fan max out at 7020-ish RPM.

The microphone on my phone is not that great, so I would judge the volume with a huge bag of salt.

 

Uploading a video with my test...
I didn't find the option to monitor fan speed

 

See attachment to enable the reading of fan speed from Speedfan.

Just in the last 15 minutes or so, I've went into the BIOS, disabled Speedstep. Carry out the same test again. Initally, the CPU had a constant speed of 2.4 GHz (great, I thought)...but during testing, once the temperature reached about 75c, the CPU clock speed dropped down to 2.1 - 2.3 GHz. Come on!!! SPEEDSTEP is disabled!!! There should be no change in CPU clock speed.

Dell, if you're reading this, please fix this!! It looks like your BIOS engineering team has decided to throttle the CPU speed. Give me the performance that I paid for!!

 

Thank you for posting the video!

Just watched your video...your CPU is VERY hot (the max column). On the plus side, your CPU spends more time in the 2300-2400MHz range...but it's still throttling.

The expectation (ideally) is that the CPU stays fully functional under 100% load at its base clock speed (2.4GHz, for i7-5500u). There is not reason for it to throttle down the speed unless it reaches close to 105c (Intel's specified max functional temperature for the CPU). Ideally, the design of the laptop should not allow the CPU to get anywhere close to 105. The laptop's exterior shouldn't get anywhere close to 40c (for human contact). The laptop's interior has to handle all the heat being generated, without performance degradation or hardware fatigue (material science and selection).

 

I found that the XPS13 (Early 2015, 9343) has the Intel Dynamic Platform and Thermal Framework (DPTF) Driver 8.0.10100.71 installed.

The Inspiron 7348 only has version 8.0.10100.24

I'm going to try this newer driver and see if it makes any difference.

Update: Version 8.0.10100.71 makes no difference. In fact, I also tried uninstalling DPTF altogether, and that made no difference either. Looks like it is coded somewhere that tells the CPU in some situation to not run at the base clock speed even when Speedstep is disabled.

 

The problem with the implementation of CPU speed throttling is that the engineers have taken away the operational preference away from the consumers, and made that decision on behalf of the users. That's a large design inconsideration / shortcut.

Some consumers want cool and quiet, some consumers want performance (me).

I, for one, want the performance that I paid for (an i7-5500u), not some sub-nominal performance that I would get with a lower-end processor. i.e. Why sell me something that I can't take advantage of?

 

Core i7-5500U
http://ark.intel.com/products/85214/Intel-Core-i7-5500U-Processor-4M-Cache-up-to-3_00-GHz

The 5500U is a 15 Watt processor. Intel's U series was designed for low power consumption. When running any application long term, these CPUs will throttle by reducing the CPU speed in order to maintain the CPU at or below the 15 Watt TDP limit.

The base clock is not guaranteed when trying to run a demanding application at full speed. The only thing guaranteed is that a 15 Watt processor should run long term at or below its 15 Watt specification and that is exactly what the LinX video shows.

Stasio has a great list of programs including the most recent versions of LinX that include the newer Linpack libraries.

http://forums.tweaktown.com/gigabyt...-info-benchmarking-stability-tools-print.html

You will probably find that LinX with Linpack 11.2.2 will work your CPU harder. Your CPU will respond by reducing the MHz further to maintain itself under the TDP power limit.

Dell and Intel should do a better PR job explaining how different CPU models respond when fully loaded.