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(radiator shown in modified form)

I remember the first time I saw these - it was on Akiba PC Hotline, the Japanese site that lists all the funky hardware that seems to appear on their market long before it does on anyone elses (if it appears at all). At the time I had just finished my original Water-Cooled Experment #1, and one of my major conclusions was that I really needed a way to cool the water down. All kinds of things were suggested, from using peltiers to cool a reservoir (and big heatsink/fan units to cool the peltiers), to just running the hose from the tap, through the system and out into the sink or backyard. None of these really grabbed my fancy. A few people used car radiators (see this notable example with a Holden transmission cooler) to cool the liquid, but I'd be completely lost in a wrecking yard and didn't fancy the idea of having to weld or saw something to fit. I spent some time looking at abandoned fridges and pondering compressors but that looked similarly hassle-prone. I wanted a small, tidy but powerful radiator.. and then I saw them available in Japan. I contacted Senfu, and their Japanese distributors, but alas, no reponse. It seemed the language barrier would kill this idea until a good friend in Japan (who wishes to remain anonymous) heard my cries for help and sent me one of the single-fan units. You know who you are, and I can't thank you enough.

I will say straight-up that getting your hands on these things right now in Australia is not easy. However, I have been speaking with Senfu over the last couple of weeks (they contacted me via the site, seems my original emails are still in a void somewhere) about distribution and I have recommended a few dealers in Sydney to them. If any of them take the bait and start importing the units it will be much easier for you guys to get them - I've no idea what the local price would be, though.

Included with the unit is a roll of waterproof tape, some small cable-ties (presumably for mounting or suspending the unit) and a sheet of 4 rubber sticky feet for the bottom. There is supposed to be an instruction sheet included but I didn't receive one.

The unit itself is impressive in the extreme. Definitely a crowd-puller at LAN parties if you mount it outside your case. It's basically a very convoluted path of copper tubing running through aluminium cooling fins, enclosed in an aluminium box with an 80mm fan mounted on one side. The fan is well sealed with rubbery foam so that all it's sucking power is devoted to pulling air over the fins and tubing inside the box. The water path basically goes back and forth inside the box, from one end to the other. My rough measurements of 120mm for each run x 16 runs gives an in-box tube length of 1.92 metres - that's just the length inside the box, not including the end U-bends. Senfu are packing a lot of surface area into such a little space. They also make a dual-fan unit, which is essentially the same but long enough to mount another fan on it. The internal length of that unit must be over 3.5M, I would think.

The fine fins that go across the entire unit. This is the air intake.

Here you can see the sealing foam for the fan. The fan exhausts air from the box.

An immediate problem I had with this unit is the small tubes they have fitted for attaching tubing to. This is fine if you're using Senfu's water-cooling kit which uses quite small tubing. Unfortunately I have been using 9mm tubing for my experiments so far, and my water-jacket will not fit the smaller tubing. I did experiment with a few methods of connecting the 2 different hoses together, including some garden irrigation tubing kits, but eventually decided to modify the radiator to fit my existing water-cooling system. This seemed as good an excuse as any to buy a Dremel, which I did, and used to great effect in cutting the thin tubing off down to the point where it connects to the thicker pipes that run through the unit. I also cut away part of the aluminium casing to allow me access to tighten the screws on the ring-clamps I used to hold the hoses on. You can see the modifications I made in the top photo on this page. The original configuration is shown below.

The original header tubes. I got rid of these to fit it into my existing rig.

Senfu have elected to use a standard 80mm fan on the unit. This is great as it allows for easy replacement in case of failure or if you have a preference for another fan. The fan blows out from the box, so it is drawing air in from the other side, the exposed-fins side. The supplied fan seems to exhaust a fair amount of air and I left it intact. It seems Senfu expect you to mount the radiator inside your case as the fan has a hdd-type Molex power connector. I would think you would want to get the heat OUT of your case, this being one of the major reasons for and advantages of water-cooling. However, you could probably mount the unit in the front of your case, as a case-front fan, but exhausting the heat out the front instead of intaking as normal for a case-front fan. This would remove the heat and allow the unit to be contained wholly within the case, presuming your reservoir is also inside. Obviously, this is something you will need to sit down and work out before building the rig. For the moment, I am leaving the radiator outside the case and using a bucket as a reservoir - in fact, apart from the addition of the radiator, the setup is the same as it was in my original water-cooling experiment.

The unit as set up for testing.

I put the radiator in the system between the pump and the water-jacket. This is different to my original thought to have the water exiting the jacket go through the radiator on the way back to the reservoir. After thinking about it, given that the water will be above room temperature anyway, the water should be at it's coldest point (nearest to room temperature) as it exits the radiator. That's the water I want going into the water-jacket. It will of course then heat up the reservoir, but it'll be cooled before it next cycles onto the jacket. I bet I get a million emails about this. :) I will experiment further, I am building the next water-cooled system as we speak and will try this radiator in various configurations.

I fired up the system to see what I could get from it. I'm not using a peltier at the moment as I don't want to seal the jacket/chip/slocket assembly up just yet and I don't want to run a peltier in these hot and humid Sydney summer days without decent sealing. I used the Soyo SY6-VBA-133 motherboard, of course, because it can monitor the internal temperature diode of the CPU. Using the same C366 as in my water-cooling and peltier experiments, I was able to run stably at 616MHz @2.2v for an entire day, looping the Unreal flyby with SETI@HOME in the background. This CPU is only capable of 583@2.1 normally with a GlobalWin FDP-32 (big heatsink/fan) on it. The temperature in my room hit a high of 27C during the 8 or 9 hours it was running and the reported on-die temperature was consistently about 9 degrees above ambient. The radiator and the water in the reservoir never felt noticeably warm. The jacket felt slightly warm. I tried it the next day with a C400. It was stable at 630MHz at 2.3v, the ambient temperature was a little warmer, hitting 28.5 degrees in my room for about 2 hours in the middle of the day. Again, the on-die temperature never rose more than 10 above ambient. With the FDP-32, and at 600MHz, this chip usually sits at about 43C.

I will point out some flaws with my rig that I'm sure are impeding the performance of this radiator. Firstly, due to the size of the cutting wheels on the Dremel, I could not cut the pipes down to where they become their full width - they are still the small diameter, but inside my larger hoses. This is definitely going to be impacting flow rate. Obviously, this will be the same if you use the unit in the default configuration so may count as a flaw against the unit. Secondly, the pump I'm using is not really powerful enough, and this is reflected by the flow rate coming out of the return pipe back into the reservoir - it's not got enough force to even raise itself above the end of the tube if you point it vertically, it just dribbles down the side, so it's pretty pathetic. With a better flow rate (read, better pump) this unit would cool even better than my results show.

This is a great unit - a very welcome addition to my water-cooled PC. It's exactly what I was looking for - it's quite spooky reading through my responses to people on the readers comments page to the original watercooling article, how perfectly this unit fits what I needed. It's very solidly made and from my results I suspect it is capable of dissipating much more heat than my rig is producing at the moment - for you guys considering water-cooled peltiers, to be absolutely safe you may want to consider the dual-fan unit as it's only USD$6.50 more (plus associated higher shipping charges etc). I will be testing this single-fan unit with a 72W peltier when I work out some of the sealing issues with the current rig, and I'm informed there's a dual-fan unit winging it's way to me from Senfu as we speak so I will obviously check that out, too.

I have to say I'm very impressed and give Senfu the big thumbs up for not only producing the unit at all, but for doing such a quality job with it. This kind of thing is exactly what the hardcore overclocking market needs, proper mass-produced products that address our unique needs and work well. I'm sure some people will complain that the elite, hardcore aspect of water-cooled PC's is eroded by mass-market products, but I think it's a great sign that overclocking is being recognized more by the industry.

Of course, one major point must be made. Water plus electricity can kill you, guys. If you're at all uncomfortable doing this kind of thing, I recommend you to stay well away from it. Experienced overclockers only need apply and even those must be extremely careful. Remember to punch yourself in the face when you start thinking an extra 20MHz or so is worth taking the risk of jump-starting your heart or burning your house down. Speed should be a passion, not an obsession, and I'm sure your family members would agree.

Again, I extend my sincere thanks to my good friend in Japan who sent me this unit and refused to let me pay for it. At your request I am keeping you anonymous. If you're ever in Sydney the beer's on me.