Latitude E7240 and E7440

Do something that gets the fan running and then load HWiNFO > Sensors (click continue to the alert about the Dell EC). You will then find the CPU fan speed under the Dell EC heading. If the fan wasn't running when HWiNFO looks for the sensors then it doesn't get reported.

The lowest fan speed on my E7440 (BIOS A10) is a slightly audible 3700 rpm with a trigger temperature of 80C. The other speeds I have noticed are 4100 rpm (trigger 81C), 4700 rpm (trigger 87C), 5570 rpm (trigger 88C) and 6680 rpm (trigger 89C). The fastest speed is very noticeable and needs sustained full CPU load (more than half way through wPrime 1024M) to get it running. The consequence of the high trigger temperatures is that lesser spikes in CPU load don't cause much fan activity - it's possible to run wPrime 32M without the fan coming on. However, Dell have also set the fan rules so there needs to be a big drop in temperature before the fan slows down so, if the fan gets spinning at 6680 rpm then the temperature has to drop below 60C before it slows down and the noise drops off.

The fan really needs to be fractionally bigger to achieve a little more airflow and avoid getting above 5000 rpm where there's a lot of increase in noise without much increase in cooling effect. Overall airflow isn't helped by the relatively small pads on the bottom of the computer so I bought some 5mm self adhesive rubber bumpers and put a couple next to the back feet. They probably helped drop the temperature by a degree or two. I have also repasted the CPU several times with the latest effort using Prolima PK-3 which some people here reckon is better than the Arctic MX-4 I had previously used.

Fortunately, I don't do much work that involves sustained full loading of the CPU. However, I think Dell could have done better - there looks to be space for a thicker fan.

John

 

Thanks John. I'm not really doing much either that would normally push the fan, which is why I'm wondering that it's coming on at all. Maybe I'll give Dell a call and see what they say.

 

the dell fan/heatsink combo is junk. From what I remember it was a tiny heatsink made of some flimsy matte black metal. Then it ran to the vent. The fan is a completely separate unit. I like Lenovo's much better as the old ones were a larger heatsink/fan combo with the fan inside the entire heatsink. I've had 2 and both came with the paste on the cpu die but no paste on the IGPU. I thought haswell was supposed to be much cooler.

 

The heatsink arrangement looks OK but the fan is only about the same thickness as a USB type A plug so the blades can't move much air. It looks like a slightly thicker fan would still fit in the notebook and would move more air for a given speed.

John

 

I thought Haswell ran hot compared to previous generations?

 

The Haswell design power ratings are slightly lower than Ivy Bridge. eg the U series CPUs are 15W instead of 17W.

However, a combination of platform design and individual chip power consumption controls the maximum multi-core turbo speed that can be sustained within the design power and thermal limits.

From my viewpoint the problem is the notebook manufacturers seem to shrink the fan(s) each time the CPU design power is reduced instead of giving the user the benefit of a computer that would run more quietly under full load.

John

 

I just got an E7440, same thing with my battery:

Code:

    energy-full:         44.6294 Wh
    energy-full-design:  48.248 Wh
    voltage:             7.434 V
    capacity:            92.5%

I noticed some battery charging options in the BIOS, has anyone played with those? I set mine to the one that is mostly AC.

I'm running Debian Sid (Jessie) on mine, it's flawless. Most uneventful new system configuration ever... just had to dump the 7260 firmware blob in /lib/firmware.

Mine has a reasonably quiet fan, idling with some chrome tabs open at around 49°C. I don't notice any coil whine or transistor squeal, and I still can hear those frequencies (just barely!).

 

Has anyone retrofitted their e7240 matte 1366 x 768 screen with a matte 1080p screen? I really like my 1080p touch but I'd like it to be lighter and of course with less glare, may even be ok with glossy finish as touchscreen seems to add a bit of weight. Also anyone know the weight difference between the 31wh and 45 wh battery?

 

Might be better off from a cost perspective just selling yours and getting the one you want. Plus, there's the possibility something might get damaged in the transition.

 

A display swap shouldn't be difficult - the procedure is in the owner's manual. Page 56 of the same manual gives the battery weights:

3-cell 250.00 g (0.55 lb)
4–cell 300.00 g (0.66 lb

John