Review of Thermaltake BigWater 735 Liquid Cooling System - Water Cooling a PC - Water Block, Reservoir, and Pump

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Twice I have used the Thermaltake BigWater 735 in liquid cooled desktop computers with a reasonable amount of success. Over the last year or so I have become intimately familiar with ever component of this liquid cooling system: Its good side, its bad side, and how to make the most of it. In this article I’ll discuss all the components of the Thermaltake BigWater 735 Liquid Cooling System in detail so you can make an informed decision about whether this kit is the one for you or not.

Water Block (5 out of 5)


The water block included with the BigWater 735 is quite impressive. It consists of a heavy solid copper block, which is an excellent heat conductor. Carved into the block is the fluid pathway, which is completely visible thanks to a plexi viewing window used to seal it off. For an added bonus, you can plug the water block into a standard fan power plug on the motherboard to enjoy your liquid cooling with the ambient aura of a blue LED.

The water block comes with several brackets which can be used to suit a variety of CPU sockets for both AMD and Intel. Most do not even require you to remove the metal plate on the bottom of the motherboard, either.

Pump and Reservoir (3 out of 5)


I’m not intending to start this review off on a bad foot, because honestly overall I’m pleased with the product. The reservoir and pump assembly just happens to be the area of the liquid cooling system that I find to be weakest. The reservoir, which I would call a tank design, is basically intended to just sit inside of the case somewhere. The pump, which is affixed to the reservoir via a solid metal and plastic tube, has much the same styling. There are slots on the sides of the pump base which could be construed as mounting brackets, but I have yet to find an effective way to mount the pump and attached radiator in any way that I found safe, reasonable, or aesthetically pleasing.

The pump and reservoir are very plain and simple, with no flash, flow indicators, fluid level monitoring, (unless you call extremely dark tinted “translucent” plastic stuffed inside a dark computer “visible”) or bonus features. The pump gets power through either a 4 pin Molex or a standard fan connector.

The biggest problem with this setup, though, is how difficult it is to customize. Personally, I would like to get a 5.25 inch bay reservoir with a flow monitor, temperature gauge, and easy fluid level viewing. Unless I want to also replace the pump, however, this presents a challenge. Because of the way the reservoir connects to the pump, the only way to really swap out the reservoir is to, instead, use 3/8’’ plastic tubing unceremoniously stuffed inside the solid metal “tube thing”. There is no barb, or screw down connector, or anything that gives you even the slightest bit of confidence that it won’t leak all over your PC, desk, and carpet. While I successfully ran with a configuration like that mentioned above for a couple of months, I eventually gave up on it.

Radiator (4 out of 5)


The PC liquid cooling radiator that comes with the Thermaltake BigWater 735 is pretty decent. It’s designed to be able to mount inside or outside the PC. It uses a single 120mm fan for cooling, meaning it isn’t very large. Though it claims to be designed to fit anywhere a 120mm fan can go, that isn’t really the case. Installing and positioning the radiator correctly is quite a challenge because of its weight and dimensions. I did, eventually, get it installed in the standard rear 120mm fan slot most mid- and full-towers have, but it wasn’t an easy process. In my larger Thermaltake Mozart Tx case I had originally wanted to install two of these radiators in the top of the case, but found that their superfluous size wouldn’t allow it - by a frustrating mere millimeter or two.

Other than that, my only other complaint is probably the fan noise. Liquid cooling systems are technically supposed to be a little quieter than air cooled systems, but that certainly doesn’t apply to this one. The stock Thermaltake fan on this radiator is not only an ugly eyesore orange, but also makes quite a bit of noise. You could eliminate that by turning the fan speed down to practically nothing with the included controller, but you’ll probably find your temperatures jumping up higher than they were when you had a simple air-cooled solution. Your best bet is to replace the fan. I swapped mine out for a $12 120mm fan with a temperature sensor, which works quite well.

After trying it both ways, I can also give my recommendation for external installation. This particular radiator, for some unknown reason, doesn’t do that great of a job at shedding heat. I found that, when installed inside of the case, my temperatures only improved by a meager 2 degrees celcius. When installed in the cooler environment outside the case, however, the difference was much more notable. Of course, so was the noisy fan which prompted its replacement.

Tubing and Fluid (4 out of 5)


The Thermaltake BigWater 735 comes with the Tt standard neon lime green tubing and fluid. Probably one of the highest UV reactive materials I’ve ever put inside my case, the unnatural coloring foreshadows the toxic nature of the fluid itself. Being a bit of an environment nut (aka tree hugging dirt worshipping hippie) I refuse to use any liquid which causes birth defects, skin irritation, and includes the number for poison control - when I can avoid it. Instead I bought a safer liquid cooling fluid: PC Ice. Since the coloring is really redundant, you can swap out Thermaltake’s toxic fluid for anything else so long as it is clear, green, or yellow, and still achieve the same UV effect. Alternatively, you can replace the tubing with the regular clear 3/8’’ vinyl stuff from the hardware store and allow your hot pink PC Ice to shine through, like I did. There really isn’t anything special about the Thermaltake tubing, besides the color. It isn’t crimp resistant, doesn’t affect temperature, and frankly not enough is included in the kit to account for measuring errors, so beware!

Overall (4 out of 5)

Overall, this is a decent liquid cooling system. It includes everything you need to get started without being overly complicated. I think the pump/reservoir solution should have been designed much differently, but it will still work for most people. Reliability is one of the most important factors in PC cooling, though, and the BigWater 735 kit offers consistently lower temperatures and has been proven to run practically non-stop for over a year, even in extremely dusty conditions, and I fully expect it to keep on trucking for even longer.