Dell :: C640 DC In And CPU Heat Sink

Jan 27, 2009

I got a defective C640, completely dead, no charging and a charged battery did not work either.

I found a bad solder joint at one of the DC filters located under the PCB just under the DC-jack, easy to resolder . Found also that the videoboard was loose. Now it is working.

But then I had a strange problem, when I put down the cpu heat sink the fan stopped, and when I just lift it a litte bit it started!?
I could not solve this until I installed the speedfan program and marked the Dell square under configure > options and rebooted?

Then I have a leftover, a plastic piece L-shaped 2+3 cm with an hole at one end,

View 3 Replies

Dell :: Airflow (heat Sink)

Jan 7, 2010

do you guys agree with this guy on the airflow?

Air gaps from Dell's stock setup of heat sinks

Now this was something I was not happy about. There is a large gap from the left fan (fan 1) to the CPU's heatsink from before. Then there was now a gap between the CPU and GPU's heatsinks. You can see in the picture above the screwdriver that is clearly visible (click the image for the full-res version).

In my history of custom cooling back in the 80s and 90s, there is one thing I learned that always remains constant: airflow is key. So my task would be to modify the airflow to force all air through the heatsinks by not allowing any to escape the airflow path through any gaps.

Aluminum Foil Shrouds

I accomplished this by using a few pieces of kitchen aluminum foil, scotch-tape, and additional AS5. There are multiple reasons for this. First for safety I evaluated the entire area and found no electrical components or circuit boards anywhere near this area. You do not want a piece coming loose and short-circuiting things!

Second is having aluminum foil allows the heat to transfer from one copper pipe to the other (just a tad though, too thin really to do a massive amount). That may not have been the best idea at first because CPUs usually run cooler than GPUs from my overclocking experience. But considering how freakin' high my CPU temps were before I even began, I could only see this as helping to offload some heat to the GPU's heatpipe - even if just a tad amount, anything had to help.

I also closed down the air escaping on the left side of fan's outlet to the CPU's heatsink, as well as the gaps between the two heatsinks. Now all air is forced by the fan trough the CPU heatsink, and then through the GPU's heatsink where it than only has room to exit the back vent.

View 12 Replies View Related

Dell :: Latitude E6400 Heat Sink

Jan 14, 2009

I'm not sure if others are aware, but I have recently found out that the contact between the heatsink and the GPU and chipset are made of a metal-foam material, while the CPU's is copper with thermal paste. After doing some research, it's said that these "high-performance foam heatsink" provide "high thermal conductivity, high internal surface area, and the connectivity of the voids". I'm not sure I'm buying into this since my idling temps are about 60C while my 9300M in my Asus U6V idles at 49C and even my 9800M GS in the Asus G71G idles at 60C.

Has anyone else seen these metal-foams used in other laptops and do you think this decision of using foam heatsinks is due to lower production costs? I personally would have preferred solid copper/aluminum w/ thermal paste rather than a piece of foam

Top red circle = chipset heatsink; lower right red circle = GPU heatsink

Close up on GPU heatsink