There are manufacturers which go for fanless and their products are not always more expensive.
I beg to differ. If we're talking PCs, they are ALWAYS
more expensive than fan-cooled, often by a big margin. This has been true for as long as I have been watching (over a decade).
As for what are "safe temps" -- this is not a good question, it is far too general. What I said -- and will say again -- is that when no fans are installed in a PC, components run much hotter than when fans are used (even super slow fans), and component life generally
This holds true for not only DIY systems but also custom-designed fanless systems factory-made by the likes of Mappit, Hush, etc. Motherboard selection becomes very important for fanless systems -- capacitors rated for higher than normal temps (105C, etc) are a minimum, to me. (For example, there were some Hush/Niveus systems which featured FIC boards years ago. I personally know of several system with these boards that died early -- mostly because mobo components failed, and also because of PSU failure.)
And to ces
: Yes, better cooling, within limits, does reduce the failure rate.
One way you could describe the difference between very low airflow systems (which is mostly what SPCR encourages) and fanless systems is that the former can be set up to provide adequate cooling even at extreme conditions, while the latter can easily slip into inadequate cooling in extreme conditions.
What are extreme conditions in normal use?
Heavy CPU/GPU load (like gaming, video encoding, etc) combined with hot weather. 30C weather is not that unusual for a month or two in a year even in temperate zones. Now, one hot summer hopefully will not kill a passively cooled system, but repeated excursions (even if short) into too-hot temps over several years -- this is what causes the damage. Think of pro athletes' injuries. Often, it's not a single big hit or injury that does the damage -- it's what exposes the long wear and tear the body part has taken over many years.
I am not espousing the kind of paranoia about temps you see in many first time posters here (and in umpteen other sites)... worry if CPU/GPU temp exceeds 60/85C after an hour of prime95/furmark. Those are extreme lab tests that substantially exceed the loads of any normal apps, and should always be considered worst-case scenarios. What I am saying is that once you have achieved a level of noise that makes the PC a non-factor in your acoustic environment, there is NO benefit (and there is possibly a real cost) to removing or slowing fans any more. Conversely, there IS often a benefit to increasing fan speed or # of fans if it can be done without increasing audible noise.