Question 1

Is this compatible with hp compaq dc-7800 ultra slim desktop computer?

Accepted Answer

If by compatible, you mean electrical (connectors voltage etc.) then the answer is yes.

If you mean physical then you need to measure the existing fans in your HP to insure that they are 60mm (about 2.4 inches) x 60mm (a fairly standard "small" fan).

This fan is quiet and moves a lot more air that most OEM fans of the same size.  I do recommend it.

Question 2

what is the wiring polarity for the red, blue and black wires (positive or negative)?

Accepted Answer

Typically they are set-up like:

Red (neg)
Blue (pos)
Black (ground)

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