SPCR

How much does it cost to not use any fans, just water cooling?

no fans, do you want to watercool the PSU or buy one of those expensive fanless powersuppllies with huge heat sinks?

Also most watercoolers have fans on the radiator, so you would probably need a biger radiator if you dont have fans.

OK, I didnt know all the details. I've just seen a picture of this guy's PC internals and there's tubes going everywhere and it's water cooled. Would it be very expensive?

It doesn't have to be but it depends on how obsessive you are about temperatures.

You'll need a waterblock for the cpu. That's gonna be at least $40 unless you want to try making one yourself.
Depending on your motherboard, you might need a waterblock for your northbridge - another $30
If you currently have a fan on your graphics card, ou'll need a gpu block - another $30
You need a pump to move all the water around. A good pump is going to be another $40
You need tubing. Good quality stuff is around $1 per yard.

EDIT: You're in the UK! For pricing look at www.pclincs.co.uk or www.over-clock.co.uk. Pricing just went up big time because this stuff costs the earth here.

Get a heatercore from a Vauxhall Nova or spend loads on a "specialist PC water-cooling radiator". Then you can run 120mm fans at 5v which is inaudible.

Take a look at the forums at pclincs or overclockers.co.uk where you will find lots of good advice and UK sources.

Bottom line is that water-cooling can be cheap (cpu cooling only, ex-scrappy heatercore) or enormously expensive.

It's just matter of how much You are willing to open your water tap... [Sorry, couldn't resist...]

Completely fanless WC system is both expensive and dangerous, if You're going to WC the PSU. Fanless PSUs are bit pricey (par with pre-modded WC PSUs), and they need a fan in some cases too.

Cheers,

Jan