I have a total of 8 80mm fans in my computer..... But I also have a vantec tornado on the cpu. It all depends on your current case temps, without us knowing those; we can't tell you squat.
teh case im getting rite now for my next pc build (cooler master cm stacker)... i will have 10 fans on there (varying sizes of course).. well that will be after some serious modding and the 10 includes the fan im getting for the copper heatsink im planning to put on the cpu
I don't have a single 80mm fan on any of my machines. All mine are eather 92 or 120mm. I'm not really fond of the 80mm. The bigger fans put out more CFM for roughly the same amount of noise.
while we are on the topic of fans, has anyone had the need to use one of those hard drive coolers that fits in a 5.25 bay? Is it worth it? Probably only for a 10,000 rpm drive, right?