1 Nickel

RE: GPU Temperature 103C on Latitude E6420

I have been in the cpu throttle zone and high temp shutdowns on Latitude e6420 (nVidia/2720QM) since upgrading to 16GB 1600mhz ram and win 10. don't know what caused this could have been the upgrade, could have been dropping the laptop and changing geometry of copper dual pipe heatsink that it already had.

Tried different thermal compounds on nvs4200m. Arctic Silver, Ceramique 2, Tunix TX-4. Finally wanted to shim it after seeing it first hand that nvs4200m doesn't connect with heat-sink to be able to conduct heat away. Was going to order 20mm x 20mm x 1.2mm height copper shim until i came across an article where someone said pennies between 1962-1980 were almost pure copper 95%. Well guess what dug out a 1980's penny from the coin sack in garage, and went nuts with  lapping it bare hands on metal sandpaper (black) until it was a plain smooth shiny piece of copper with no Lincoln image and no memorial "request to be pardoned Mr. AbLincoln" sandwiched between nvidia and heat sink with a dab of Arctic Silver 5.

Pre Fix Temps

idle - 72-75C

Load - 100C and it would shutdown. Typically while watching High Res movie or Youtube 

Post Fix Temps

idle - 50-55C

Load - 68-72C 

Furmark Burn in max temperature reached  - 92C vs 100+ and shutdowns earlier.

Positive side effect is also on processor cores, all of those run 45-55C now compared to 55-78C earlier.

I can 100% confirm that a properly lapped penny from 1980's causes a 20 Degree difference in both idle and load temps. It also causes 10 Degrees drop on Furmark Burnin Test.

I confirm that using dell supplied drivers vs nVidia latest ones caused no change in temperatures. This was attempted because of a mention that dell drivers were tweaked to their hardware architecture and worked better. Finally with penny fix, use latest nVidia Drivers without fear of over heating.

Firmware change idea as logical it was did not help with temps. I changed quite a few firmware's including A21 and the latest A23, even went back all the way to A04 and had to jump through A08 to get back to A23.

I am almost certain that most of that ebay copper shims cannot have the same purity as a penny. I would trust a penny more than Chinese metal :-) and moreover when you are stuck with this problem you don't have 3 weeks for a Copper Shim to arrive from China or Hong Kong.

If you have dremel and vise to hold the coin please do use it for lapping penny, Saying this as I forgot to use mine and have a couple of blisters right now on fingers. The Lincoln Memorial side is a quick lap but the dips around Lincoln image buff out last. Very satisfied with this fix.

Try it out if you are handy or have a friend who is mechanically inclined. 



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