If no fans spin up then it's probably the power supply. I'm not familiar with Gateway, but I know this is an old unit and it probably takes an older AT style power supply and might even be proprietary to Gateway
I didn't see anything on this website baring people from contributing here. Mods feel free to delete if this is the case.
I would say from the name it is a FlexATX setup. This means it would use an ATX powersupply.
That being said, there is an easy way to see if your power supply is dead. Unfortunately, since it I can't tell if it is a proprietary variant of an ATX psu, so I won't share it for fear of you shocking yourself.
There is something else to look for. BAD CAPACITORS. Computers from this time period were PLAGUED with horrribllee capacitors. A good website to see some examples is badcaps.net. Now that being said, in your case these could be the problem or a symptom of them going bad in the power supply AS WELL as on the motherboard.
Edited by PedroDaGr8, 26 November 2008 - 01:45 PM.