ok lets work this through
1x12 = 12 columbs of charge stored
1 amp = 1 coloumb per second
start engine 3 secs max
this means the capacitor can output 4amps for the 3 secs it takes to start a car...
55W low power supply for VIA EPIA m/b draws 4.5amps at full load, running at less than full prob be about 4 amps
i dont have any farad capacitors handy, but someone that does might wanna have a go !!
ps. tell me if any of my maths is dodgy lol