I use a 1977 Pontiac Bonneville heater core for my rad. It's solid copper, and twice as thick as a PA120.3 rad, and it cools just about the same - and I can fit it in a cosmos. I had a great idea about making a custom shroud for the heater core, used a t-shirt and some resin mixed with fiberglass and created a nice custom shroud:
And then my retarded ass realized it wouldn't clear my waterblock on the motherboard, so I just tossed it in the closet, never could use it.
At the time I took the photo I was using an Eheim 1260. I now use a DD5 variable DC pump. However, that Eheim ran in my computer for 8 years straight, only turned off for about 4 hours total combined. And it was still working the day I removed it. I just can't stand the sound, that's why I'm water cooled. I have run a phase change setup before, but I didn't like the sound of the compressor clicking on and off all the time at night. I preferred a custom peltier water chiller I made. The only bad thing is you need two separate loops, and your computer weighs about 150lbs. My current rig in the picture weighs just about 100lbs.
Heres a pic from a few years ago using my water chiller:
It was fun, but turning on the computer caused all the lights to dim, and using almost 2kW for your computer got old fast. And, it increased the temperature of my room by about 20* F, which in a texas summer is unbearable.
I was into machining my own waterblocks out of copper billet, but It became rather expensive. I did make a thread on hardforum several years ago on how I melted down $5.00 in pre-76 pennies into a copper block and then machined it into a GPU block. But, I got tired of constantly havign to change things for new systems and chipsets - went out and bought some danger den hardware which fucked me (their reservoir wasn't even glued together, leaked water all over the damn place). So if you're interested in it, fuck danger den. Swiftech or Dtek makes great stuff.
Now I'm running a AMD 965 Black edition which I won at quakecon 2009. First time I've ever owned a non-intel system in my life. My computer only has 2 120mm scythe magnetic bearingless fans which are dead silent. I can hear the capacitors on my ram at night, that's quiet.
It does cool quite well, my delta is about 10*C on all my components, however they do idle at higher temps than air (which is usual). My hardware tends to outlast most peoples that are air cooled, even when it's overclocked considerably. But, like I said I am primarily interested in water because of the quiet, and lack of maintenance, I have to put some distilled water in it about 3-4 times a year, and blow out my radiator 4-5 times a year, which takes just a second.
For simplicities sake, I'd recommend just doing air cooling if you can bare the noise. Water cooling will cost you a fortune, but once you have decent components it's only a small expense for the gains. But, Roliath clearly has too much heat with all those cards, you'd need a full tower with 2 gigantic rads and 2 separate loops, probably run you over $1,000 to do it correctly. Adapters, barbs, interconnects, blocks, and tubing is where it kills you.