Noiseless
My workstation, equipped with a 2.8GHz P4 (HyperThreading) and a Radeon 9800, is able to run graphic-intensive games (such as Oblivion etc.) without any increase in noise. The noise level is about the same as a person whispering at the other end of a large room
This is achieved by the following cooling solution:
My LianLi case is equipped with a single 120mm Scythe (fluid-bearing, 800rpm) fan (which is noiseless, even when held close to the ear), as well as the 120mm fan in my 500W Seasonic PSU. No further fans are in the case. These provide a low, but necessary air-flow to any components not otherwise activly cooled, including the PSU, the voltage regulator, the passive heatsink on my chipset (Intel, so it doesn't get very hot) and the heatsinks on my paired RAM sticks (2x1Gb PC3200 CL2).
My CPU and GPU and the two fluid-bearing harddisks are cooled by waterblocks. The GPU block (Innovatek, since AquaComputer was out of stock) also cover the VRAM and other GFX chips, which is important these days! The harddisk blocks are probably unnecessary and is primarily there to provide some additional cooling of the water, as the harddisks are mounted close to the air-intake.
I use a Reserator 1 (old, blue model) to cool the water passively. On this I've mounted a RF1 (Reserator Fan), which is only started (by SpeedFan) when the CPU or GPU temperatures rise due to intensive gaming etc. When running at all (which is only after long periods of high load) I run it at just 25% to keep the noise down (allowing the game sounds to block it out).
Since the pump inside the Reserator is apparantly mounted incorrectly (at least in the old model?) It broke after about a year. I've now mounted a MAG pump inside my case instead. Aside from providing a much higher waterflow, this pump also allow me to monitor the pump rpm, as it provides tacho-output through its fan-connector (I guess it could even be speed-regulated, only the motherboard connector I currently use doesn't allow this). I removed the old pump from the Reserator of course, to prevent it from restricting flow.
Note that both the two harddisk water-blocks and the external fan on the Reserator aren't really necessary, except for very high performance hardware. As such I'm sure my system would run just fine without these (though I guess a PC with a faster CPU and one of the latest SLI GFX cards would likely need the Reserator FAN, especially if you want to overclock, which I personally find unnecessary).
Beware that many motherboards only provide limited power-ratings for their fan-connectors, and as such it may be necessary for pumps using fan-conncetors (such as my MAG) to be connected using a molex-connector instead (be sure to use one with a tacho pass-through connector though,so you can monitor the pump). Such a connector was included with my MAG pump, but having an Intel motherboard, which provide 25 Watt on the CPU connector, I'm not using it.
I can HIGHLY recommend water-cooling, especially using a passive (external) radiator, such as the Zalman Reserator or similar solutions available from various companies. Not only does it provide MUCH higher heat-removal than ANY air-based cooling solution, but it also prevents overheating to a much greater extent. As such, I can switch of my pump entirely for extended periods (up to one hour), without any components reaching critical temperatures. With the pump running, my CPU never goes beyond 45 deg.C. while my GPU will stay below 60 deg.C. (and this will likely get much lower, once I remount its waterblock using a proper thermal compound) These temperatures are WITHOUT the fan on the radiator running (with this at 100% the CPU stays below 40 deg.C.) And this is despite the fact that I still use the, rather poor, CPU water-block that was included with the Reserator 1.
Another, seldom noted, benefit from water-cooling, is that it is CHEAP!!! This is not immediatly apparant, as a complete water-cooling solution is indeed somewhat more expensive than a similar air-cooling solution. However, the fact is that fans tend to have a limited life-span, especially if your PC isn't in a "clean-room" (moreso if you, like me, smoke a lot). The same, although to a lesser extent, can be said about the heatsinks, since these tend to get covered in dust and dirt, which can be difficult to remove completely (note that even a very thin layer of grime, not to mention tar and nicotine, will impair performance to an unexpected extent). On the other hand, most water-cooling equipment will run for years without any significant performance-reduction. Thus you will likely be able to re-use your water-cooling components through several hardware upgrade cycles, whereas most fans and heatsinks will have to be replaced on a yearly basis (or at least cleaned thoroughly).
In relation to the above I want to note that I've not used the most expensive parts, by far. The conclusion is that you don't need the most expensive water-blocks, nor do you need a very powerful pump (my old one was 5W, the new one is about 18W) or a super-efficient radiator, in order to achieve better cooling than even the most expensive and high performance air-cooling solutions. This of course, unless you want to overclock your hardware to rediculous levels, in which case air-cooling isn't even an option.
Also, in my experience, water-cooling is much easier to maintain, as you can get away with changing water once or twice a year (which is easy if you use an external reservoir, such as the Reserator). In fact I didn't change my water for more than two years, which is not recommended (lots of strange stuff in the water when I finally changed it), but this just shows how resilient water-cooling really is (my cooling-performance was only slightly lowered at the end, and probably more from the slowly dying Reserator pump than anything else). If you plan to change water at long intervals (ie. more than six months), I can highly recommend adding a few drops of whatever anti-corrosion and/or anti-algae fluid you use once in a while (say, every three months or so).
The biggest surprise in this regard, was when I opened my case for the first time in two and a half years, only to find that not a single speck of dust had been deposited on my hardware components or inside the case. Being a heavy smoker, I'm used to seeing several centimeters of brownish dust and grime inside my previous air-cooled PCs, and that after just a few months of operation. I should mention that my current PC is the first to have any kind of air-filter (included with the LianLi case), but then again, I'm sure my old air-cooled PC wouldn't have liked this kind of "blockage", preventing the high air-flow necessary to keep its CPU below the 70+ deg.C. it used to run at!
You will, of course, have to take care not to spill water onto your hardware, but even this isn't quite as difficult as it may sound, if you just take a little care when taking apart your system. In fact I once did a stupid thing, by blowing into the water-hose to empty it while forgetting that it was disconnected inside the case! Luckily only a few drops of water remained in the hose, and neither my motherboard nor my GFX card seem to suffer from the shower (I made sure to wipe them off and let them dry before restoring power of course). To prevent damage to the expensive components, should this kind of "accident" happen again, I've now purchased a special cooling-fluid which isn't electrically conductive. Since I've yet to exchange my water with this, rather expensive, fluid, I can't say if it is as good as water (few fluids are better than pure water, when it comes to removing heat!)
I hope my experience will encourage some of you to go for a water-cooled solution the next time you decide to upgrade your PC. Nowadays you can even get quite cheap, completely factory-sealed, water-kits, where you don't ever have to change the water and which should be as easy to mount as your average heatsink+fan kit (just don't expect these ready-to-run kits to be nearly as effective as a system you put together yourself!)
I certainly know that I'm NEVER going back to those noisy, short-lived and unreliable fans. Rather I plan to water-cool my fileserver as well, even though it isn't placed in my living room like my workstation and therefore doesn't need to be as quiet. Still, just to get the peace-of-mind and increased cooling-performance, I plan to use the old water-cooling parts for the server, when I decide to upgrade my workstation.
