[airspirit]

You will not be able to use a bong. If you attempt that with a 5x1 bong, you will burn your CPUs within an hour, and that is NOT speculation. It WILL happen. You need large radiators. A large car radiator will be aluminum, since there is NO SUCH THING as a copper car radiator unless you're willing to spend thousands. Keep that in mind when debating the type of radiator.

Your cheapest method is using the Lytrons. On second thought, if you are keeping it outside, you can construct the box for under $80 USD in Canada due to low wood prices, and you'll spend $120 USD on the radiators (getting a good deal at EBay on Lytrons). The PVC, if you JUST make a tall vertical tube and drill out ports for the computer lines, and use a single manifold on the bottom for the three radiator loops and the 1.5" bypass, you should spend less than $60 USD. If noise isn't an issue, you can use two cheap shop fans from WalMart or the equivalent for $40 that will provide about 3000 CFM, but at 55-65 dB. Mounting the fan cages shouldn't be difficult if you plan your frame construction right.

That would leave you at $300 USD for the entire setup, minus tubing (use braided inside the box!!! You need the strength!!!), and all you would need is tubing to the PCs and water blocks.

Building a bong of the size you're describing would cost around $100 USD (PVC of that size is extremely expensive, as it is only used by water districts, commercial enterprises, and large farming applications), and wouldn't do the job. Relatively, this isn't a large price increase when considering that this is the path of least resistance to get you the maximum gain.

Also consider that purchasing a used radiator will cost around $100 USD alone, will be damaged, and will most likely be corroded thereby limiting your cooling ability (notwithstanding the fact that it is aluminum). A new vehicle radiator will cost upwards of $280 USD for the cheapest one of the size you'd need (light truck sized).

BTW: Why the hell would you want to put 10 machines on one loop? Is this for home use (for LANs) or for business? Is it a rackmount system? Consider the length of tubing you'd need if you were populating a large area with computers. Also consider that if these are going to be added and removed regularly for lans, that you will either need blocks that are easy to remove (see my method in my article), or you will need quick disconnects on the lines. Also consider that if you ever only run a few blocks at a time (with disconnects), that you will burst your hosing due to pressure from the pump. You will need all ten blocks on to bear the pressure in parallel in order to avoid that, so I would recommend easy to install/remove blocks that are never removed from the cooling loop regardless of their installation status (it also makes maintenance SO much easier!).

BTW, 10 3/8" loops will provide about 1.5" ID of flow when combined. 3 Lytrons at 1/2" only provides about .9" ID of flow. That is why the bypass will be necessary to ensure your blocks won't be starved in that configuration.

Shoot, if you were closer to me, I'd even help you build such a beast!!!