Zalman Reserator1 Fanless WC System

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Aug 3, 2004 by Russ Kinder

Reserator1 Water cooling system
Market Price
$249.95 at Sharkacorp (who kindly provided the review sample)

Image courtesy of Zalman

From the first time you see it, it is obvious that the Zalman Reserator1 represents something completely different on the PC cooling landscape. The first impression is accurate: The Reserator1 is completely different:

For one, it is Zalman's first complete water-cooling system, previously they've sold their waterblocks only as individual components.

Secondly, it is the first totally passive water-cooling kit to be widely available commercially.

Thirdly, its almost totally silent.

The concept is elegant in its simplicity: Use water as a medium for moving the heat of the CPU a much further distance than what is possible with a conventional air-cooler. Once freed of the confines of the area directly around the CPU, the options for then transferring the heat energy from the water to the air are greatly expanded.

Conventional air-coolers, as well as most water-cooled systems, use a fan to force air across the heatsink/radiator fins to accomplish this transfer. The Reserator1 replaces the forced air movement with natural convection. Convective airflow is nowhere near as efficient as forced air; the volume of air passing over any given part of the heatsink is simply much lower. Zalman balances the reduced efficiency by greatly increasing the available surface area for heat transfer, and by configuring the shape to take maximum advantage of the convective airflow.

The system consists of two essential primary components: The radiator/reservoir/pump unit, and the CPU waterblock, and comes complete with all the assorted accessories needed.

Image courtesy of Zalman

We'll start with the small bits:

  • 3m of surprisingly high quality 12x8mm silicon tubing, in color coordinated blue, of course.
  • 4 hose clamps for (relatively) leak-free disconnecting of components.
  • Disconnect fittings for PCI slot opening. While perfectly serviceable as-is, I would have liked to have seen an actual PCI slot cover included, with pass-through holes, in with the kit. A small quibble, but it would be nice to not have to leave the open slot on the back of the case.
  • Instruction manual.
  • Flow Indicator tube.

Image courtesy of Zalman

When up and running, the activity in the flow tube is the only indication that the user has that the pump is running, so its inclusion in the kit was a smart choice. There have been some reports of flow tube cracking during assembly or use, but our test sample performed as expected, with no troubles. At the time of publishing, Zalman is offering a recall on the plastic flow tubes, and is exchanging them free of charge for one with stainless steel fittings.

The depth of the accessories package is further indication of the Reserator1 being targeted towards the novice watercooler, rather than the expert. The manual that is included is very thorough and well written; it could walk someone completely new to water-cooling through the entire assembly process, from start to finish.

Now on to the big parts of the kit.


The true heart of the entire system, the Reserator combines the pump, the radiator, and a reservoir into a single unit. It is essentially a deeply-finned water-filled tube of extruded aluminum, with a pump submerged at its base. All of the aluminum has been anodized a deep, iridescent blue.

From Zalman:

Reserator is a compound word derived from 'Reservoir' and 'Radiator' - it acts as a reservoir while radiating heat. This product works well with natural convection and integrates a water pump inside for convenience

Radiation Area
1.274 m2
6.5 kg
150 (dia.) x 592 (h) mm
Anodized Aluminum
Coolant Capacity
2.5L max.
Water Pump
5W, Qmax 300L/h
Maximum lift

As a design element, this thing is, dare I say, pretty. Obviously aesthetics are probably not top on the top of the list of requirements while selecting PC cooling components, but there is something to be said for design quality. And since you'll be looking at this unit for the entire time it's in use, having it look good is at least a nice fringe benefit.

A good angle for understanding the finned nature of the Reserator. There are 44 fins in all, each 2.5cm deep, and tapering from 2mm's thick at their base to 1mm at their tips.

Image courtesy of Zalman

Moving down to the base, you can see the water line connections, labeled to avoid confusion.

Disassembling the unit reveals the pump. The pump is attached to the base of the Reserator by means of a pair of stainless steel screws and strap. Instructions are included in the manual for replacing the pump with an external one, should the user desire.

As water-cooling pumps go, the compact Eheim unit mounted inside the Reserator is a relative lightweight. A comparison of the 80gph and 18” head of the Reserator's Type 300 pump to the commonly used Type 1048 pump's 158gph and 59” head is a pretty powerful indicator that the Reserator is going to be a low flow system, in any configuration.

Much is made of flow-rate in the world of water-cooling. Put simply, it is the water-cooling equivalent of air-cooling's airflow, measured in Cubic Feet per Minute. Like CFM, flow-rate is an important indicator of cooling performance, but it is not the only indicator. As we've seen with conventional heatsink testing, designs can be optimized to perform under low flow. How well the Reserator1 performs will largely depend on how well Zalman's engineers designed the system to accommodate the flow rate dictated by their choice in pumps.

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