Ok I'll bite. Here's my mining rig:
Wait... we'll have to look deeper.
Here's the case: From top to bottom, we have: Radeons 6870, 5970, and 5750. The top two are watercooled and the 5750 is just a piece of crap thrown in for lulz. Note the wonderful use of garden-rated PVC tubing+connectors on the 5970 and the patented Bubble-Loop(TM) that prevents all the liquid draining out of the 6870 waterblock. Despite having two watercooled cards they are not amazingly overclocked or anything, it was mostly to keep them quiet and cool.
What is the crazy blue thing bottom left? Well its the two reservoirs ($4 Ikea storage containers) for each cooling loop. There is a total of about 4 liters (including tubing volume: substantial) in the top reservior (for the 5970) and 3 liters in the bottom reserviour (6870). The cooling fluid is distilled water saturated with borax (sodium tetraborate) which has been filtered to remove sodium oxide. I won't explain why I've done this. Suffice to say that nothing biological known to science can grow in this solution, it's fairly stable and harmless from a chemical perspective and aluminum is stable at it's pH which is roughly 9.7. The solution is colourless and transparent when prepared. (There is about 1 kg of borax solid dissolved to make the solution for both reservoirs). It has a 1 watt LED array that was like $0.80 on ebay to light it up. The little box I made that sits on top is an on/off switch for the light and also one of the pumps.
So why are they blue if borax solution is colorless to start with? Well the 5970's cooling loop has two radiators that I use. One is for winter (shown below) and the other is for summer, which is installed outside and runs through some tubing installed through the floor. The outside radiator is substantial in size, and has 8 meters of internal tubing length alone and several m^2 cooling fin surface area. The inside radiator is smaller but still probably overkill. It is 40x30x3 cm in size roughly. The total tubing length in winter for the 5970 loop is ~9 meters (15 in summer) and the 6870 loop is ~10 meters. The flow rates of both are less than 1 liter per minute (very low in terms of PC watercooling, apparently). The blue colour comes from copper ions leaching out of the brass or copper that the radiator(s) are made out of (the tubing is copper or brass but the fins are aluminum). The temps are pretty good on the cards, the cores of the 5970 are currently (25 deg C ambient) at 41 deg C with a slight overclock, more importantly VRMs sit <80 deg C. The 6870 is at 47 deg C with the pump spinning so slow it is silent, it drops to high 30's when the pump runs at its normal speed.
Despite the relatively high electrical conductivity of the solution, because of the stupidly long tubing distance between the waterblocks and the radiators (which are dissimilar metals in each case, subject to electrochemical processes ie. corrosion) I have measured the conductance between them and only nano-ampere currents can pass between the two (which is good!).
One of the pumps (which I fully expect to drop a hose and leak badly one day) and masses of tubing running behind the HTPC.
In winter the radiator used to cool the 5970 loop is installed on the back of the air intake of a portable conditioner that runs 24/7 in fan mode. It uses about 30 watts. Its good to move air around the room too, dispersing the warmth from the 5970
You'll marvel at my amazing placement of coolant lines carrying highly conductive solution right above several bunches of 240v cables, connectors, powerboards etc. However I have confident that these connections won't leak because it has ran this was for more than 2 seasons now.
In the corner you can see three tubes running through the wall/floor, two are the coolant lines for the summer radiator and the third is just the air conditioners water drain. The black/red cables beside it are to power the fans on the summer radiator.
The 6870 cooling loop is a much more recent addition and I setup this extremely dodgy looking radiator to leak test the system and do some other performance tests. I made some crazy electronics to control the pump speed by toggling between 5v and 12v rails from the PSU but eventually found it was not sufficient for my needs, so instead the $8 pump now runs of $200 lab bench power supply until I can be bothered fixing it up 'properly'. The OUTRAGEOUS amber mass next to the radiator (which has 4x 120mm fans ontop) is because of an absolutely ridiculous air-bubble-sucking problem I encountered where the pump was pulling such an extreme vacuum on one half of the cooling loop that it was pulling air between the tubing-connector join near the radiator. One hour with a hot glue gun and several zipties putting kilograms of force on it didn't solve it. The solution was to move the pump position in the loop and lower its voltage a little.
For now it tentatively lives on the glass shelf under my TV.
Last thing perhaps worth mentioning with all this highly electrically conductive coolant around the place and dodgy agricultural grade tubing/connectors being used... is the amazing drip-mitigation feature I have installed to protect the lower-lying cards in the case. As you might be able to see, it is in fact a collection of disposable drinking cups cut up and taped together to redirect any liquid to the bottom and out of the case! $2 of plastic may yet save the $100+ cards! Wheee!
