Have you ever used a power generator to run a PC?

Yes I used one,

In one of my contract I have to work on the site and the electricity was made with a small essence fuel generator 8-12 hp. The only thing I can say: it's better to have ups attach to your computer, because sometime they have huge fluctuation in the electricity. The ups I have clean the power line and even if the generator run out of fuel I have at least 45-60 minutes to close everything.

Well we had a 28 hour power outage and the huge generator in the carpark kicked in and ran the building for that time - does that count?  

Seriously though, +1 to jive - generators are not the most stable of outputs - a decent (read APC) UPS is almost mandatory for a decent power supply. The APC monitoring software regularly shows our input voltage off the mains dipping to 202v (I'm in the UK, we should be getting ~240v) - the UPS may rarely kick in, but it's always smoothing the line, which seems to help component longevity.

Yes - from 3 - 5 hp and 15 kw to 150 kw generators.

You do not need "truly 'clean' power. "Stable" is more important. The first thing a computer PSU does is turn the input directly into DC.

Best answer selected by liquidsnake718.