As you can see, the stock AMD cooler is quite capable of keeping things under control at stock speeds. However as voltage and speed increased, temperatures quickly climbed out of control. By the time the CPU exceeded a 20% overclock and .3v over default, the cooler was no longer able to keep things stable and the system crashed at 65° C.
Next up, the Bigwater 760i with fan on low.
Whereas the stock cooler temps begin to climb rapidly once speed and voltage increase, the performance of the 760i is very linear. Air coolers tend to absorb and release heat fairly quickly, however water takes a lot longer to heat up and cool down. Loads were applied for 20-30 minutes or until temperatures stopped climbing to ensure accurate readings. 250mL is not a lot of water in this system and heat soak accounted for several degrees. That is, initial temps were noticeably lower when the CPU was first loaded, then slowly climbed as the liquid absorbed heat until a balance was reached between the efficiency of the radiator/fan and the amount of coolant in the system.
Now let's crank the fan up on high.
Running the fan at a now-audible level, temperatures were improved by 1-2° C across the board. While not exactly loud enough to be annoying, it is definitely noticeable and probably not worth the small extra benefit to cooling. Even on the low setting the 760i performs on par with high-end air coolers I've reviewed recently and runs nearly silently while doing so.
The Thermaltake Bigwater 760i was by far the easiest liquid cooling system I've ever installed. It's almost ready to go right out of the box, and needs only two sections of tubing cut to fit and attached at either end. The water block installs just like most any other heatsink, more quickly in some cases as it doesn't require changing out the backing plate for socket AM2. If you can squeeze a ketchup bottle you can fill this system with water, and there's no messing around with mixing coolant or having to run out and buy distilled water. The system turns on and off with your computer and bleeding the air is just a matter of running it until all the bubbles disappear.
Rather than perform a leak test with the unit outside of the computer I found it much easier just to disconnect the power supply from the computer and jump-start it with the green-to-black wire trick. Might be nice if Thermaltake would suggest this method somewhere in the instructions, it's much simpler than trying to connect everything up outside the case, then disconnecting it and reconnecting it inside once the test is done. This is the method used by other water-cooling kit manufacturers and it works quite well.
The issue I had with the mounting of the water block should probably also be addressed. Without stops of some sort or clear instructions on how tight to make the screws, this has the potential to damage some hardware if the installer starts cranking them down. A little bit of common sense is required here, by alternating the tightening of the screws to opposite corners to make sure it pulls down evenly and turning them just until the clip begins to bend.
Performance-wise the Bigwater 760i works very well, matching or slightly exceeding the best results I've obtained with other high-end heatsinks. And without much (if any) of the noise normally associated with air cooling. After checking around it appears the 760i will run you somewhere in the neighborhood of $150 which is two or three times the cost of a typical high-end air cooler, but pretty cheap as far as liquid cooling setups go. For the money you definitely get a well-made and good-performing, all-inclusive water cooling kit that's a snap to install and maintain. Can't ask for much more than that.
Thanks to Thermaltake for providing the Bigwater 760i for review.