Watercooling for PC’s is not a new concept but as CPU’s become more powerful and generate more heat, new watercooling kits and components are popping up faster than ever before. There has been a huge rise in the popularity of watercooling in just these past 2 or 3 years, mainly due to cheap and easy kits hitting the market in relative abundance. Still, while there are good and cheap complete kits available, much like buying a stereo, if you want the best you buy separate components.

Now while waterblock design varies from manufacturer to manufacturer, and there are new ideas and designs of waterblocks appearing on a somewhat regular basis, the rest of the cooling system hasn’t changed all that much. We have different sizes of radiators appearing now and then, but apart from that the rest stays pretty much the same. However one growing trend is the idea of a reservoir that will also aid in the cooling. For Zalman that would be the Reserator. WACC brought out the pretty universal P/A Res we reviewed a while back. Innovatek had one although it seems to have dropped off the map and even ThermalTake has their Rocket watercooling system.

Around 6 months ago, we took a look at first twin sized radiator, the R120-D and were suitably impressed. At that time, XSPC had only 3 items in their line-up but have been busy since then expanding to include all the components of a watercooling system, including a Passive Aluminium Reservoir setup to be used not only with their own components but any existing watercooling setup as well.

Specifications

Passive Aluminium Reservoir
- 250mm Anodized Aluminium Tube
- 260ml Capacity
- Acrylic top and base
- Chromed mount
- Removable Blue LED (4pin molex)
- 1/4" Thread
- Weight 700g
- Dimensions: 280x70x70mm
Supplied with mounting kit, available currently in 3 colours - Red, Blue and Black

XSPC, don’t have any fancy packaging for their products, just a box with a single colour label depicting the contents. However everything is packed well, with the box above arriving in a larger, bubble wrap filled box with some other components. In the case of the XSPC Passive Aluminium Reservoir, you receive the reservoir itself, two mounting rings, and various nuts and bolts as well as a Blue LED to put in the base. As far as connection options go, that would be down to the reseller but the base of the reservoir has ¼” Thread to take barbs, compression nuts, push fittings and the like.

Before we get straight to looking at the reservoir, I want to take a moment to comment on the O ring mounts supplied. XSPC have supplied these with a foam inlay and chrome effect, so they not only protect the reservoirs anodized coating from scratches, they also look good while doing it. The downside is of course they are very susceptible to fingerprints but I think it’s worth the trade off in cleaning them.

I’m looking at the anodized Red version of the XSPC Passive Aluminium Reservoir, which has a finned circumference with a clear acrylic cap at either end. Both caps unscrew easily enough to allow you to fill the reservoir from the top/attach the barbs to the bottom. One thing I would like to mention about the base is that when it comes to the barbs, make sure you get those with the smaller ‘wrench turns’ as larger ones will prevent you from screwing in the base all the way and cause a leak.

When you take the top cap off and look down inside the reservoir, we can see that the inside is smooth and that one of the water channels in the bottom base has a tube attached. Unscrewing the bottom we can get a closer look at this tube. The tube is there to make sure that water returning to the system is deposited in the reservoir away from the outlet so as not to pass the warmer water directly back into the system via the outlet next to it; an obvious but none-the-less good idea.

Also in the base is a small hole, aligned centrally and ready to accept the supplied Blue LED. The LED is wired and ready to go; all you need do is plug it into the power. It doesn’t have a pass thru connection so you will need a dedicated power plug for the LED, and should you not wish to use the LED at all then you simply don’t install it. I have heard that UV LED’s are infact not true UV at all (having never used them I don't know for sure), however it does spring to mind that with a hole in the base ready to accept an LED, you could conceivably use a UV LED and a UV reactive dye for an interesting look. It also looks pretty good from the top too.

One thing I do want to point out is that like any cylindrical reservoir, there is nothing stopping you from mounting this horizontally as opposed to vertically, although you will need to have the reservoir in the vertical position to fill the system obviously.

Like the R120-D radiator that we looked at a while back, this reservoir also feels and appears to be constructed to a very high quality. It is kind of difficult to translate that with the pictures, but I can assure that there are no machining marks, burrs, scratches or other unwanted manufacturing errors of any kind.

Test Setup

Intel Pentium 540, Intel 955X, Kingston HyperX PC2-5400, Albatron 6600GT, Hiper Type-R Black Label 580w PSU.

Watercooling Setup and Flow Order

XSPC DC1000 Pump > XPSC Zern CPU Waterblock > XSPC Passive Aluminium Reservoir > XSPC R120-D Radiator > XSPC DC1000 Pump

For comparison purposes we will run the exact same setup, minus the XSPC Passive Aluminium Reservoir, but using a simple acrylic tube reservoir instead. As with all temperature related reviews we do, the system was allowed a few days to bed in and settle down, then readings were taking both from idle and under load multiple times, with the temperatures averaged out for the final results. Results were taken when the room temperature was 27C (+ or - 0.5 C) and any other results ignored. For idle, the PC was warm rebooted and left doing nothing for 15 minutes before taking a reading. For load testing, SiSoft Sandra 2005’s CPU Burn In Wizard was used and ran for at least an hour. Temperatures were taken using a Lian Li temperature probe placed next to and touching the CPU and on the inlet and outlet tubing of the reservoir to measure (as best I could) the temperature of the water before and after cooling with the reservoir. Temperatures are measured in Celcius.

CPU Temperatures

Ok, so it would seem it makes only a little difference to the CPU temperature? Well yes and no. This is the same thing we have seen with other small aluminium reservoirs that are designed to aid in cooling (they do aid in the cooling, but due to their passive nature the temperature drop isn’t a major one). They don’t really come into their own until you lower your radiator fan speeds, so let’s test the system again but this time lower the fans speeds from 12v and 2400rpm to 4v and 1700rpm. Note that both results below include the passive reservoir in the loop, only the fan speeds have changed from High to Low.

Again, the temperatures have not changed all that much however do bear in mind we have lowered the fan speeds and therefore the noise output of the system. Running the fans at 4v means that the fans put out very little noise, with only the actual air moving being audible. Temperature wise we get virtually the same temperature as without using the reservoir and running the radiator fans at highest speed. So the bottom line here is that while it doesn’t drop your temperatures significantly, it can help to maintain low temperatures in a low noise setup.

Taping a temperature probe flat to the tubing, as close to the reservoir barbs as possible to measure the temperature at those points will give us some idea of the water temperature, or if nothing else let us see the differences in temperature under different conditions.

Fans High

Fans Low

With the fans on the radiator set to low, the passive reservoir has to deal with warmer water, and it does it quite well considering the size and capacity of the reservoir. The difference in the temperature between the inlet and outlet is just under 1C at load but every little bit helps. With the radiator fans set to high, the reservoir is already dealing with cooler water and the temperature difference is lower.

Final Words

There is a lot to like about the . It’s easy to install, looks great and helps to keep your noise levels down. The manufacturing of the reservoir is of a very high quality which is something we have noticed with other products.

The reservoir body itself is made from aluminium, anodized, (available in 3 different colours at time of writing) with multiple fins around the circumference of the body for passive cooling. The two end caps are made from clear acrylic and both simply screw into the body for a waterproof seal. The bottom cap has the inlet and outlets as well as a hole for an LED; supply a pre-wired blue LED that you can choose (or not) to install.

The mounting arrangement has also been thought through with chrome effect O rings, inlayed with foam to protect the reservoir body from scratches and not detract from the appearance.

When it comes to its performance as a cooling aid, the differences are minimal until you lower your radiator fans speeds, in which case you find that that Passive Reservoir lets you keep the noise down without taking a temperature rise hit as a result.

Lastly, it is quite inexpensive in comparison with other non passive reservoirs and other cooling components on the market.

I would like to see the base cap become a little thicker, so that should you inadvertently get barbs with large turns, they won’t prevent you from tightening the bottom cap properly. This can be avoided by simply getting barbs with small turns but with a thicker cap that moves the inlet and outlet holes further away from the reservoir body, this would become an irrelevant point. I also would like to see different lengths available as with a longer reservoir body, the overall surface area will increase and cooling potential should rise allowing you to further lower fan speeds and noise.

Pros: Looks great, Easy to install, Universal – just get the correct size barbs/fitments for your existing setup, Pre-wired LED supplied, Chrome O rings with foam inlay to protect reservoir body for mounting, Helps you keep fan and noise levels down, High quality of manufacture, Inexpensive

Cons: Must use small wrench turn barbs/fitments or bottom cap won’t screw in properly

Bottom Line: Since this is a passive cooling device it won’t make huge reductions in the temperature of your watercooling setup. What it will do is keep the temperatures low even when you lower your radiator fan/noise levels, allowing you to further silence your system. It’ll look good doing it and won’t cost a bomb either.

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