Thanks a bunch Godprobe! From the referenced thread:
The AxeFx is designed to operate in ambient conditions up to 50°C; the processor is designed to operate up to 85°C.
The TigerSHARC processor only dissipates a few watts of heat, but that's large in relation to their small surface area. That's a fact of life with all modern processors. The TigerSHARC is rated to operate with its skin temperature as hot as 185°F. The die inside the chip can be even hotter than that, and it will still operate.
btw, 85C and 185F are equal.
I realize this is a can of worms to Cliff, having designed for worse-case like 110° F+ outside, fierce sun load and being racked above a stack of power amps. To publicly 'authorize' a small minority to cheat is only asking for trouble. Having read that thread again now I don't expect a blessing from Cliff - I wouldn't offer one either.
But.... on the other end of the spectrum there are guys like me who are far away from this operational extreme. The problem for hard-core studio owners is that beyond 'a guitar box', the Axe holds its own against many of the high-end processors, and it’s only the fan noise that limits acceptance as one. It may be hard for some to realize that a 'little fan' could cause so much grief, but also realize that most all studios budget
significant build costs to establish a respectable noise floor. The last thing a conscientious owner wants to do is fire up something with a fan that can be easily heard (and recorded) on an everyday basis.
The temperatures that cobbler measured with the 11 shows a large safety margin may exist for the best-case situation, and if the temperature limit indicated in the old thread is valid there may indeed be a no-fan solution for some of us. Got a feeling that some numbers specific to the Ultra may appear soon....
You can also get Fan Speed Controllers which sit inline between the fan and the motherboard - the controller bit with the speed dial can be left outside the lid (if you make a hole for the cabling). You can then turn down the fan speed at will when required and back up straight afterwards.
Some time ago I made a little voltage divider and played around with the stock fan to see if a reasonable drop in fan speed would work - nope. Doing this with the 'fan of choice' seems to be the best alternative if the no-fan thing proves scary - thanks. I see just one option for venting the top and that would only be in conjunction with a no-fan situation.
Hope I'm not aggravating your ulcer Cliff - really.