Zalman’s Reserator 1 fanless water cooler

Manufacturer Zalman
Model Reserator 1
Price (street) $201
Availability Now
THERE WAS A TIME that that the guttural growl produced by my dual Pentium III workstation was music to my ears. I was running a pair of PIII 700MHz chips overclocked to nearly 1GHz in a monstrous tower brimming with close to a dozen 80mm system fans, and the machine sounded every bit as powerful as it was. With all the fans spinning away at full throttle, you could hear the system coming from a mile away, and that was just the way I liked it.

My how things have changed. Today, I cringe at the noise produced by most systems and wonder how much hearing loss I suffered at the hands of my old workstation. Of course, I haven’t gone completely soft. I still drool over high-performance systems overclocked to their limits, but I prefer a stealthier approach to cooling that shuns fan-infested full tower cases in favor of smarter and quieter designs.

This fascination with quiet cooling started out innocently enough, but it’s rapidly blossomed into an obsession as I try to integrate PCs into other rooms in my home. In the Benchmarking Sweatshop, I can deal with the inevitable hum associated with processor activity. However, that hum becomes a distracting annoyance in the living room and bedroom, leading me to seek out a completely silent cooling solution.

My search for silence led me to Zalman’s Reserator 1 fanless water cooler. Standing nearly two feet tall, the Reserator cuts a mean profile on the horizon, but can the fanless radiator keep a processor cool in the steamy confines of the Benchmarking Sweatshop? And more importantly, can it do so while barely making a sound? Read on to find out.

Cue Thus Spake Zarathustra

The monolith

The Reserator towers over a cube

The Reserator’s defining feature is a massive radiator that measures nearly two feet tall and about six inches across. Depending on your tastes, the radiator will either be an ugly eyesore or an interesting piece of functional industrial sculpture. I tend to lean towards the latter, but perhaps only because I have a fetish for anodized aluminum. Speaking of anodizing, the Reserator comes in any color you want, as long as it’s blue. I quite like bold colors, so the blue doesn’t faze me. However, it’s a shame that Zalman doesn’t offer the tower with a more subtle black or silver anodizing that might be more appropriate for home theater systems and traditional decors. Anodizing protects the Reserator from corrosion, so it’s more than just a cosmetic treatment. I just wish a more palatable color were available.

If you can’t stand the Reserator’s metallic blue color, you can always tuck the tower away in a corner or behind a house plant. There’s no getting around the tower’s size, though. A tall tower with loads of surface area is essential to the Reserator’s fanless design, which relies on natural convection currents to dissipate heat. As the Reserator’s temperature exceeds a room’s ambient temperature, heat flows from the tower to warm the cooler surrounding air. This warmer air rises up the height of the tower and is replaced by cooler air from the rest of the room, creating a subtle air flow without the assistance of fans. With a two-foot tower, the Reserator definitely has loads of height to encourage natural air flow. The tower’s 44 cooling fins also provide a whopping 1.23 square meters of surface area to dissipate heat.

However, the tower’s reliance on natural convection makes me wary of the Reserator’s ability to handle warmer climates and higher ambient room temperatures. Zalman cautions against positioning the tower next to heat sources or in direct sunlight, too, which makes me wonder if the Reserator can handle the 30-degree Celsius temperatures typical of the sweltering Benchmarking Sweatshop.

Although the Reserator relies on natural convection to dissipate heat, transferring warm fluid from the system processor to the cooling tower requires a pump. If only convection worked as well with water.

Staring down the barrel of the Reserator

To keep fluid flowing, Zalman straps a 5W water pump to the bottom of the Reserator’s cooling tower. This little pump is nearly silent, especially when the tower’s 2.5 liter coolant capacity is topped off. Rated to flow 300 liters per hour, the pump should be more than powerful enough to keep water moving through the system as long as things are relatively level. The Reserator’s maximum lift is only half a meter, though. Installing the tower too far above or below a system could impede or even halt fluid flow.

If the Reserator’s 5W pump doesn’t have enough muscle for your needs, Zalman provides the necessary hardware and instructions for the pump’s replacement or removal in favor of an external unit. Of course, Zalman takes no responsibility for performance losses that may result from using an external pump that’s not compatible with the Reserator’s plumbing. Keep in mind that a beefier external pump may compromise the Reserator’s low noise levels, too.

Plastic screw-on fittings at the base of the tower

The Reserator’s plumbing is anchored to the cooling tower with a couple of plastic compression fittings. The fittings are easy to use and feel more secure than spring-based clamps that could loosen with time or continued use, but the plastic feels a little cheap next to the metal fittings used elsewhere in the system.

A block for every socket
Speaking of metal fittings, here’s two of them on the Reserator’s water block:

Mmmmm. Metal fittings.

The Reserator comes with Zalman’s ZM-WB2 water block, which consists of an aluminum cover and a gold-plated copper base. Using an off-the-shelf water block makes it easy for those with dual-processor systems to find matching water block for a second processor. Zalman also offers GPU blocks for graphics chip cooling.

A nearly perfect mounting surface

The water block’s copper base is polished to near perfection, though a number of fine scratches are visible if you look closely enough. Proper thermal compound application should ensure that these minor scratches don’t impede heat transfer between the processor and water block, and Zalman provides a tube of thermal compound with the kit.

Although a near-mirror finish and metal fittings are nice, the Reserator water block’s most intriguing attribute is compatibility with a wide range of CPU sockets.

Mounting hardware for just about every socket

The block ships with mounting hardware for Sockets A, 478, 754, and 940. It should also be compatible with AMD’s new 939-pin socket, which uses the same heat sink retention bracket as Sockets 754 and 940. The water block’s one mounting restriction pertains to Socket A, where a motherboard that conforms to AMD’s optional four-hole heat sink mounting design is required.

Despite that one limitation, the Reserator’s water block is generally well-behaved across all CPU sockets. The block takes up considerably less room than standard Pentium 4 or Athlon 64/Opteron coolers, and the mounting screws are carefully threaded to ensure that the block isn’t screwed down too hard. Limiting the number of threads on each screw prevents the water block from crushing a processor core or damaging a motherboard. However, even with the screws tightened as far as they’ll go, the water block is just loose enough to rotate slightly from side to side. Mounting hardware keeps the block centered, and there isn’t nearly enough play to break contact with the processor. However, some may prefer a tighter fit.

Putting it all together
The Reserator depends on water flow through the system to channel heat from the processor to the cooling tower. Without this water flow, processor temperatures could climb to dangerously high levels.

Keep an eye on flow with this handy indicator

Thankfully, the Reserator comes with a handy in-line indicator that makes it easy to confirm that water is flowing through the system. When water is flowing freely, the orange lead vibrates slightly. When it’s not, the lead is still.

Of all the Reserator’s components, the flow indicator is probably the flimsiest. The indicator’s plastic body and hose fittings are a stark contrast to the Reserator’s otherwise metal components, which makes the indicator feel a little out of place. Still, the indicator is easy to install, leak-free, and essential for paranoid types like me. I’d also recommend using Motherboard Monitor or a motherboard BIOS to set CPU temperature warning and shutdown levels on the off chance that a pump failure or flow problem occurs when the system is left unattended. To be fair, I make the same recommendation for air-cooled systems.

Plenty of tubing

To connect its various components, the Reserator comes with three meters of 12x8mm silicone tubing. The flexible tubing is easy to run through a system, just be careful not to bend it at extreme angles that could produce flow-restricting kinks.

Metal fittings and clamps

When installing the Reserator, you have a couple of options for routing hoses from the processor to the cooling tower. If you don’t plan on moving the system or replacing fluids with any regularity, you can run hoses directly from the water block to the cooling tower (with the flow indicator in-between, of course). The silicon hosing will easily fit through an open case expansion slot or any hole larger than 12mm in diameter.

For those who move their systems regularly or want to be able to separate the cooling tower from the rest of the system without draining it completely, Zalman provides a pair of PCI expansion fittings and hose clamps. The fittings are secured to a case’s expansion slot like so:

Fittings from the outside…

And from the inside

To separate the system from the cooling tower, clamp the tubing on both sides of the PCI fitting and remove the hose from the external fitting. The clamps do an excellent job of stopping water flow, although I wouldn’t want to leave the tubes pinched for an extended period of time for fear of creating a permanent kink. If you’d rather not crowd a system’s PCI slots with hoses and fittings, you’re free to drill your own holes and mount them elsewhere in a case. In your system is crowded with multiple PCI devices, custom holes are probably the best way to go. The fittings are easy enough to mount in a PCI slot, but they’re also wide enough to potentially make contact with solder points and components mounted on the back side of PCI devices mounted directly below them.

A handful of spares, just in case

A handful of spare parts rounds out the Reserator’s hardware. Zalman provides a spare compression fitting, cable fitting, and O-ring in addition to a sealing bolt that’s necessary to run the Reserator with an external pump.

Our testing methods
All tests were run three times, and their results were averaged, using the following test systems.

Processor Athlon 64 3200+ 2.0GHz
Front-side bus HT 16-bit/1GHz downstream
HT 16-bit/1GHz upstream
Motherboard Abit KV8 Pro
North bridge VIA K8T800 Pro
South bridge VIA VT8237
Chipset driver VIA Hyperion 4.51
Memory size 512MB (1 DIMM)
Memory type Corsair XMS3500 DDR SDRAM at 400MHz and 2-7-3-3 timings
Graphics NVIDIA GeForce FX 5200
Graphics driver ForceWare 56.72

Western Digital WD1200JB 120GB 7,200RPM ATA/100 hard drive

Operating System Windows XP Professional
Service Pack 1 and DirectX 9.0b

We tested the Reserator’s performance against a stock AMD cooler and a ThermalTake Silent Boost K8 heatsink/fan. The system was set up on an open test bench with ambient room temperatures between 28 and 31C. Prime95’s FPU-intensive torture test was used to generate a high heat CPU workload.

We used the following version of our test application:

The test systems’ Windows desktop was set at 1024×768 in 32-bit color at a 75Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests. All of the 3D gaming tests used the high detail image quality settings.

All the tests and methods we employed are publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.

Noise levels
An Extech 407727 digital sound level meter was used to measure our test system’s noise levels. The meter was placed six inches from the open test bed at idle and after 10 minutes of our Prime95 load. When testing the Reserator, the water tower was placed directly next to the test system.

Although not all motherboards can manipulate processor fan speeds based on system temperatures, our test system can. The KV8 Pro’s FanEQ variable speed fan controller was enabled during testing, resulting lower fan speeds and noise levels at idle. Under load, FanEQ cranked both the stock and Silent Boost coolers up to their full speeds.

The Reserator’s water pump isn’t variable flow, so it doesn’t get any louder under load. Our air coolers do, and they’re much louder than the Reserator with Prime95 cranking in the background.

Although hard drive and power supply noise prevent the Reserator from achieving lower system noise levels, the cooler itself is nearly silent. You can hear the pump if you put your ear right up against the water tower, but that’s about it. Still, it will take a quiet hard drive, a passive graphics cooler, and a silent power supply to bring the rest of a system in-line with the Reserator’s faint noise levels.

CPU temperatures
I had my doubts about the Reserator’s ability to cool a loaded processor consistently over extended periods of time, especially in my steamy Benchmarking Sweatshop, so I subjected our coolers to a 24-hour marathon of testing. The test started innocently enough with half an hour of idling. Next, the system was pounded with 22.5 hours of Prime95’s maximum heat torture tests followed by an hour of cool-down with the system running at idle.

Testing was conducted over three consecutive days with ambient room temperatures consistent within a degree from day to day. Ambient temperatures varied between 28 and 31C across the length of each day.

Over our 24-hour torture test, the Reserator managed much lower average and maximum temperatures than the stock and Silent Boost air coolers. That’s no small feat considering the steamy conditions in the Benchmarking Sweatshop. Here’s how temperatures stacked up across the full 24-hour test:

At idle, the Reserator is only marginally cooler than a stock AMD heat sink/fan. However, the Reserator managed much lower CPU temperatures across the load portion of our test and leveled off at a relatively cool 53C.

CPU/System temperature differential
Because convection is so dependent on ambient air temperature, I’ve also graphed the CPU/System temperature differential of each of our cooler configurations. On an open test bed, system temperatures should be proportional—though not identical—to ambient room temperatures.

Looking at our CPU/System temperature differential confirms that simple convection, with a little help from a water pump and massive cooling tower, does a much better job keeping our Athlon 64 3200+ cool than our stock or Silent Boost active air coolers. There’s a much smaller gap between our system and CPU temperatures with the Reserator than with either of the air coolers we tested, which is enough to quell my fear that warmer climates and higher ambient temperatures would cripple the Reserator. I’d certainly heed Zalman’s warnings about putting the tower in direct sunlight, though.

Since concluding my Reserator testing, I’ve had the cooler running on a Pentium 4 2.4GHz for nearly 72 hours straight. Instead of running Prime95’s maximum heat torture test, the system is slogging through WMP9 video encoding and [email protected] The system is sitting in a closed case in my slightly less-steamy living room, and CPU temperatures haven’t eclipsed 51C. And from eight feet away, the system doesn’t make a sound.

Our benchmarking groupies can’t get enough
of the Reserator

Given how easy the Reserator is to assemble and how well it works, even under a constant load in a relatively warm room, I’d be inclined to pick one up for every system I own. Seeing giant blue towers all over my apartment might take a little getting used to, but I could deal with it.

Unfortunately, my credit card couldn’t. The cheapest price I’ve found for the Reserator online is $201, with most vendors selling the cooler for between $250 and $300. There’s a hefty price to pay for silent water cooling, although compatibility with a wide range of socket types at least ensures that the Reserator will work with multiple systems.

Apart from the Reserator’s high price and love-it-or-hate-it aesthetic, there’s not much to complain about. I’d rather see the cooler’s plastic fittings replaced by metal ones, but for consistency’s sake rather than any concern that the plastic fittings are prone to leaks. Of course, just because I can find few faults with the Reserator doesn’t mean that the cooler is appropriate for all applications. Those looking for a high-flow water cooler for serious overclocking will likely be unimpressed with the Reserator’s performance. I suppose one could always use a high-output pump and rig a fan or two to blow air across the cooling tower, but such a configuration would compromise the Reserator’s low-noise design, and that’s what the cooler is really all about. LAN gamers should also stay away from the Reserator, not because it’s difficult to detach the cooling tower for transport, but because the tower weighs close to 20 pounds when filled with water. Its weight and less-than-compact design make it a big of a chore to lug around with any kind of regularity and quite inconvenient for a LAN gaming rig.

If you’re not a LAN gamer or a serious overclocker and are unfazed by the Reserator’s price tag and aesthetic, I suspect you’ll be quite happy with the cooler’s performance and noise levels. The Reserator is barely audible and does a fantastic job keeping processors cool under extended and extreme loads. Perfect for bedroom PCs and home theater systems, the Reserator is even appropriate for gaming rigs and workstations.

As impressed as I am by the Reserator’s performance, I’m even more encouraged by the fact that Zalman was audacious enough to create and market such a product. The Reserator is easily one of the most daring and innovative cooling products I’ve ever seen, and given the cooler’s full “Reserator 1” name, it looks like Zalman is just getting started.

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