Surge

if hit by a spike in voltage, depends on the magnitude and duration the damage could be the psu, motherboard and cpu etc.
is your mc still boot?

There may be NO physical evidence.

If the PC does not boot up, or operates in an erratic manner, a surge or ESD event is a possible root cause.

The PCs that I have worked on after lightning strikes ALL had visible damage.
Start with the modemor network card.
Look for signs of bulged or scorched components.

Next, look at the large capacitors and transistors near the CPU on the motherboard for the same.

A blown fuse is another good sign of a surge.
(there is a non-replaceable fuseinside many PC power supplies)
CAUTION: there are dangerous voltages present inside the power supply.
It should only be opened by a trained technician!

Chas

I had to replace modem, sound card & cpu fan. The cpu fan was still running! but running very rough. The cpu fan could have been just worn-out.
Computer boot's up so far.What I like to know,if a computer that has ESD still run OK?