building a computer

[Pamela]

Don't do what I did once and forget the dielectric grease under the CPU cooling fan. Everything looks perfect, I closed up the box, set it upright and powered it on.

It began booting, then the fan fell off and the expensive CPU burned out seconds later. DOH!

[glatt]

My brother gave my son a Rasberry Pi for Christmas along with a circuit board that can control motors. They powered it on and ran it for a while downloading software and then smelled a slight smell of smoke. My brother touched the processor on the motor control to feel if it was warm, and he burned his finger. Pulled his hand away, and actual flames shot up from the control board's processor. (Small ones, but real flames.) Turns out he had ordered the wrong motor control circuit board to go with the Rasberry Pi. The smell was pretty bad and his finger hurt for a while, and he wound up buying a new different motor control board a few weeks later and sending it to my son.

My son hasn't tried out the new board yet.

[limey]

Originally Posted by glatt

My brother gave my son a Rasberry Pi for Christmas along with a circuit board that can control motors ... a slight smell of smoke ... actual flames ...

That uncle. The exciting one. He'll never be forgotten!

[tw]

Originally Posted by Pamela

Don't do what I did once and forget the dielectric grease under the CPU cooling fan. Everything looks perfect, I closed up the box, set it upright and powered it on.

Dielectric grease it is not. It is electrically conductive. Therefore too much thermal compound can cause CPU defects.

Had that heatsink fallen off an Intel, then no damage results. That problem exists with AMD processors.

Meanwhile, a heatsink attached without any thermal compound means CPU temperatures should only be single digit degrees higher. An excellent test of whether a heatsink was properly machined.

Selecting a heatsink involves specification numbers such as 'degrees C per watt'. What others recommend is irrelevant compared to spec numbers.

Today, all above is made irrelevant by CPU manufacturers that already attach a best and sufficient heatsink.

An oldtime engineer later (and accurately) said, "If you touch it and don't leave skin, then it is not too hot."