In response to gmat:
"I repeat, extending the MOSFETs is harmless, there is absolutely *no* reason it could harm the PSU..."
I mostly agree. The mosfets are a capacitive load to the driver IC, and are probably only compensated/driven as such. Very long leads, like across a whole tower case to the other end, might add enough inductance, that combined with the mosfet's capacitance, at the high switching frequency, would risk 'dulling' the sharp square wave switching signal. I can imagine those fets spending a long time in transition from off to on to off. Those mosfets only handle the power because they switch too fast to spend much time as a transitional load. An uninformed but compitent and adventurous electrician/hobbiest (wires own house etc.) could inoccently make the mistake of saying "Hey, I have heatshrink, I have #12 lead wire, I have insulating shims, and I have a neat home made copper water block with space on it for those mosfets, so I'll just put some 2 foot wires on and roll up the excess later." Poof? I'm sure that 6" leads wouldn't do much harm, but I would want to do some extensive bench testing with an oscilloscope before I went out past a foot or two long.
I think that as is often the case, staying within reason is what is really required here. Maybe as a rule of thumb stay within the psu case dimensions, and make the mosfet leads just long enough to do the job. That should be short enough to not cause any big trouble.
And keep a fire extinguisher handy LOL
As for ATX specifications, compliance, etc... The issue here is Electrical Codes
. In Canada the laws say "You can't sell things without CSA approval." The insurance companies follow along and say, "We won't pay your insurance claim if an electrical fire is caused by a non-CSA approved device." Most other countries are probably similar. If you modify an electrical device, you void it's CSA approval, and having a CSA'd PSU burn after
modding it, burning your property, could put $$ $$ in the eyes of an insurance claims lawyer. Maybe it would be best to lie and say "bought it that way" or try to call attention elsewhere somehow??? Anyways, who wants a fire. Insurance is not the answer to fires. Prevention is. Maybe a small automatic fire extinguisher is available and inexpensive, to go inside a PC case to limit the potential damage. Strikes me as a good idea with any wooden enclosure like Rusty's desk, or plastic like Mike's breadbox. I don't know how well it would work, but I'll be looking into it. Rusty may have beat me to the punch on the desk idea, but I'll be catching up with my own furniture creation eventually, and I would like to play it safe. I'll post my findings.
It's nice to see the diverse opinions and attitudes co-exist so peacefiully and constructively on these forums, with no flame wars etc..
Cheers to all!