Hi!

First off, my system is 99% similar to this one here: http://parker1.co.uk/mythtv_silent.php

The only difference with my system is the GPU and the PSU.

As above, I plan on making this PC a MythTV box. i have been in contact with the owner of the above box, and he said that the PC is silent, and i was 99% sure I would just change my PSU to be the same as his (as my current PSU is noisy) and I would be set... but... then I began to wonder.

How fanless can I go. In the PC (both the linked example and mine) there is only the one fan, in the PSU. This pulls enough air through to cool the system.
I thought about using a fanless PSU. But having no fans at all in the setup might not be a good idea? So maybe a Fanless PCU but a silent case fan to pull air through.

Or a PSU with fan and no case fan?

Im rambling on a bit. my question is: What would you think was quietest? A Fanless PSU and a 120mm Case Fan or a Silent PSU with 120mm fan and no case fan?

I'd go for the first option: there will be less turbulence noise.

The first option would also probably pull more air through the Ninja

I would expect there to be very little difference between the two setups acoustically, you may not even be able to tell the difference depending on the sensitivity of your hearing and where you sit in relation to the PC. Also, fanless PSU + case fan will be a lot more expensive than fanned PSU + no case fan. If you absolutely must have the quietest setup, the fanless PSU is the right option, but it helps to consider if you will be able to notice the difference (ie what is the level of background noise etc). Also bear in mind fanless PSU's can have heat issues (understandably).

fanless psus seem to be tricky (heating problems, less reliable - my guesses), also you can end up with crackling and buzzing from the psu.

additionally, if the ninja is within an inch of the psu bottom, it should still get some wind. these are only my guesses - i never tried such a setup before (i have a fan in the back and a fan in the psu right over the ninja - both pretty close to the heatsink)

mmm, how about a semi-passive psu - e.g. tacens valeo - i read some good opinions (and bad ones too! but fewer of them). it only starts its 13,5 cm fan when, hmmm, when, hmm, some people say when you get 60 C inside it or when it draws > 40% of power. not really sure how they work.

i went for option 2

I think ill go with the PSU with a Fan. The reasonbeing that I may (if i like MythTV a lot) move the PC into a HTPC case, in which case I will need good airflow and I ddont think a fanless PSU is best!