Alphacool NexXxos X2 Bold Highflow water block Page: 1

In the very recent past AMD and Intel have been vocal about upcoming families of multiple core CPU's which will take processors into an area that we have never seen before. With Intel's current Q6600/ QX quad-core range and AMD's soon to be released Phenom native quad-core processors on the horizon, eight and sixteen cored processors will no doubt follow as the process is perfected and applications demand it.

It is a well known fact that water-cooling is really beginning to become a viable mainstream alternative to traditional air-cooling measures. No longer is water-cooling purely the domain of the hardcore overclockers, but ever increasingly it is beginning to make its way into more and more people's homes.
With the advent of quad-core processors and the successful saturation of the market with dual-core processors as well, a need has arisen for cooling methods to tame these multi-cored beasts. So how do we look towards cooling these processors more efficiently...With water-cooling of course!

Alphacool webpage

is a name synonymous with water-cooling hardware. The German based company made a name for themselves by producing quality, well-performing hardware for the PC enthusiast. However, in recent times it seemed that they simply dropped off the radar, allowing competitors to muscle in on their hard-earned market share.

Today, a revamped Alphacool seeks to restore itself back to the position that it held in the past, and continue on with manufacturing high-quality hardware as a commitment to both their current dedicated fan base and you, the prospective customer. The effort being made by Alphacool to regain lost ground is evident. From the fresh and enticing web page, through to the updated product lines, Alphacool is on a mission!

Today I have been given the opportunity to review the new Alphacool NexXxos X2 Bold HIGHFLOW waterblock which promises the highest performance nozzle waterblock with return flow channels, and enormous flow. Considering the exceptional performance of the current cooling champion, the D-TEK FuZion, it will be interesting to see how the Alphacool NexXxos X2 Bold HIGHFLOW performs. Will it tame the Quad-core beast?
Alphacool NexXxos XP Bold HIGHFLOW


The new Alphacool X2 Bold HIGHFLOW's specifications were unashamedly taken from Alphacool's product page

(L x W x H)
50 x 50 x 18mm
(water block)
330g (approx.)
Flow Rate4.9 to 5.0 L/m
294 to 300L/h
Material:Copper base and Plexi top
Mounting:Socket 775
Fittings: (cooler is supplied without fittings)G1/4” (BSPT 1/4") 8/10/13mm

Now that we've seen the new Alphacool NexXxos X2 Bold HIGHFLOW's specifications, let's head over the page to check the waterblock out in a little more detail...

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Packaging and Contents

When I received the new NexXxos X2 Bold waterblock it came in a bubble pack reminiscent of those used by memory manufacturers, but just a little deeper to accomodate the waterblock.

Alphacool NexXxos X2 Bold packaging Package contents

Chris Banks (International Sales and PR Manager for Alphacool GmbH) has told me that they are currently in the process of renewing all the packaging for their product lines, and when the new packaging is available it should look something like this.

Alphacool packaging

Included in the Alphacool NexXxos X2 Bold HIGHFLOW packaging are:

* 1 x Alphacool NexXxos X2 Bold HIGHFLOW waterblock
* Mounting hardware
* 1 x syringe of thermal paste
* 1 x installation manual.

Everything is included in order to get your CPU water-cooling well underway with the exception of barbs. Be sure to order them through your online retailer or you may encounter an obvious problem.

For the first-time watercoolers amongst us the installation manual is written in German. However, the images that Alphacool has included in the manual should be more than enough to make installation a breeze.

A Closer Look

The Alphacool NexXxos X2 Bold HIGHFLOW waterblock belongs to the 'semi-impingement' family of waterblocks. Whilst not a true jet impingement waterblock like the Swiftech Storm, it does utilise a nozzle insert to accelerate water turbulance around the cooling pins.

First impressions are usually lasting ones...and the Alphacool X2 Bold  is very stylish to say the least and it allows for the insertion of coloured/ UV LED's into the perspex top if you are so inclined.

Alphacool NexXxos X2 Bold accelerator nozzles NexXxos X2 accelerator nozzle and base

Accelerator nozzle Accelerator nozzle reverse
The accelerator nozzle plate looks extremely slick. However, I can't help but imagine that the 53 nozzles will somehow impede the overall flow rate of the waterblock - especially when it is marketed as 'HIGHFLOW'.

The copper base of the Alphacool NexXxos X2 Bold HIGHFLOW has been treated with glass beading to maximise the cooling potential of the surface.

NexXxos X2 mirror finish NexXxos X2 showing width
The mirror finish is second to none even with the protective plastic still in place. The relative low-profile footprint of the Alphacool should hold it in good stead by ensuring compatibility with a plethora of motherboards. I installed the Alphacool NexXxos X2 Bold waterblock on both an ASUS P5B Deluxe wifi/App and an ASUS Blitz Formula SE motherboard, and I am happy to report that there weren't any issues relating to compatibility.

NexXxos X2 kitted out with barbs
With the Alphacool NexXxos X2 all kitted out and ready for installation, the build quality is very apparent. Personally I'm a sucker for perspex and the visual bling afforded by it.

Angled barb
One issue that I did encounter with the Alphacool NexXxos X2 Bold waterblock was that the barb thread on the inlet side was not cleanly tapped. When I went to insert the barb it went 3/4's of the way in before becoming extremely difficult to tighten. After a little bit of ingenuity on my behalf and some lubing up courtesy of a local bar of soap, the barb then began to tighten down properly. However, the barb doesn't sit quite right and subsequently pitches to the right quite noticeably. The pitch doesn't cause any leakage issues with the compression ring, but it is something to look out for .

Anyway, let's head over the page to see how we're going to test the Alphacool NexXxos X2 Bold HIGHFLOW waterblock...

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Test Setup

For the testing phase of the review I have chosen to test the Alphacool NexXxos X2 Bold HIGHFLOW against a well known water-cooling block, the XSPC X2O Delta. A Laing DDC Pro pump with OCLabs alternative top will be used to assist in making a comparison. I shall be looking specifically at pressure drop, flow resistance and cooling performance from within a water-cooling loop. All tests will be run 3 times to ensure the elimination of any oddities.I have included the setup details below:

Pressure Drop

For the pressure drop test I used a 25L portable water container filled with 20 litres of water, with a 1/2" plastic threaded barb placed in the bottom to represent the reservoir. A stop tap was inserted immediately after the 1/2" barb to allow for a faster water-block change. The True-Flow pressure meter was used to record the head pressure per 1 minute testing cycle. The pump was primed and let run for a short period to ensure that no air bubbles were left in the loop. The water was allowed to run back into the container after passing through the pressure meter meter via a 'T' connector in order to minimise wasted time between water-block changes.

The first run made was with only the pump and pressure meter included in the loop and the water pressure noted. Then for second run the Alphacool NexXxos X2 Bold HIGHFLOW waterblock was included into the loop and the drop in loop pressure recorded. The same procedure will be followed for the XSPC X2O waterblock.

* 1 x Laing DDC Pro pump with OCLabs alternative top @ 12v
* 1 x Alphacool NexXxos X2 Bold HIGHFLOW and XSPC X2O waterblock
* 1 x Powertech variable DC power supply (quoted accuracy /- 0.2V)
* 1 x Multi-meter
* 25L portable water container
* 1 x Glycerine filled True-Flow pressure meter. (kPa/PSI)
* 1/2" ID XSPC tubing
* 1/2" barbs
* 2 x stop-tap fittings


In a similar test to the pressure drop testing above, the flow test will highlight just how much the waterblocks restrict the natural flow of the watercooling loop. Utilising a very simple setup consisting of a pump, I/2" ID tubing, waterblocks, bucket and a stopwatch we will see how far removed from the absolute flow of the pump, that the waterblocks hinder flow.
Running the pump into the bucket for one minute and then measuring the amount of water pumped will be the 'absolute flow' of the pump.

To calculate the flow-loss or restriction of each waterblock, they will each be included into the loop (one at a time) and the same procedure followed. The flow rate will be recorded in Litres/ hour. All simulations will be run 3 times each to ensure uniformity of the results and an average then taken.

Loop Simulation and cooling performance

I have decided to impliment a control setup for the testing phase of this review. In doing so I have replicated a watercooling loop similar to that in conventional water cooled setups, but also one that should return consistant and unbiased performance results. The open loop that I have chosen to run with will use be semi-restrictive in nature, but again should give quite a good indication of how the Alphacool NexXxos X2 Bold waterblock would perform in your system. The Alphacool NexXxos X2 Bold's performance will be assessed at the Laing DDC Pro's operating voltage of 12 volts. For each run, the pump was allowed to run for 20 mins to ensure the evacuation of all air from within the loop. The temperatures were taken at 30 minute intervals to allow them to 'settle'. Two instances of ORTHOS will run simultaneously in order to simulate load.

Arctic Silver 5 TIM was used instead of using the syringe supplied in the Alphacool NexXxos X2 Bold packaging. I have recorded temperatures at idle, load and and an overclocked loaded state; all temperatures were taken using Core Temp 0.95.4 beta and water/ambient temperatures were taken using a common household mercury thermometer. The mercury thermometer was allowed 5 minutes to aclimatise to air and water and then the temperature recorded. The setup used has been included below:

* 1 x Laing DDC Pro pump with OCLabs alternative top @ 12v
* 1 x Alphacool NexXxos X2 Bold HIGHFLOW and XSPC X2O waterblock
* 1 x Powertech variable DC power supply (quoted accuracy /- 0.2V)
* 1 x Multi-meter
* 1 x Tribal Overkill reservoir
* 1 x Toyota Camry heater core
* 2 x Scythe Minebea 120mm cooling fans
* 1/2" ID XSPC tubing
* 1 x Swiftech MCW60 GPU block
* 1/2" barbs.
* 1 x Intel Q6600 SLACR G0 stepping quad-core processor
* 1 x ASUS P5B Deluxe wifi/App motherboard (bios version 1101)
* 1 Palit 8600 GT graphics card
* Logitech generic mouse
* Logitech G15 keyboard
* 2GB OCZ PC2-6400 Titanium RAM
* Antec NEO EarthWatts 500W PSU
* 250 GB Seagate SATA II HDD

Please follow with me over the page to see the test results...

Alphacool NexXxos X2 Bold Highflow water block Page: 4

Pressure Drop
Determining pressure drop for water-cooling components is really quite easy and should give the prospective purchaser some idea of how well or how badly a particular component restricts/resists the natural flow of a pump. This is especially important when designing your water-cooling loop to ensure that your pump flow doesn't come to a crawl because of your cpu block, gpu block and possibly chipset block. Factor into the equation a reservoir, various curves and connectors and the amount of pressure drop can become an issue. Hence the reason why we need to assess for pressure drop.

Head Pressure

You can see from the above graph that both the Alphacool X2 NexXxos and the XSPC X2O Delta recorded the same amount of pressure drop The reson why this has been recorded as such is simply because my current flow meter measures down in increments of 1 kPa. Both of the waterblocks actually recorded pressure drop less than 1 kPa, but in order to measure it accurately would require the use of a digital pressure gauge which exceeds my budget at the moment.  The pressure drop experienced by the Alphacool X2 Bold Highflow would most certainly be attributed to the 'accelerator nozzles' in the inlet. The X2O Delta on the other hand simply dumps the coolant into the waterblock, which it then has to fight its way through all those densely packed copper pins on the way to the outlet. The end result is a loss in pressure.

The graph below further illustrates how the Alphacool X2 Bold HIGHFLOW waterblock's accelerator nozzles hinder flow. With the Laing DDC Pro with OCLabs top pumping out nearly 800 Litres of water an hour at 12v, the significant significant drop in flow can only be attributed again to the accelerator nozzles. Remembering back to basic science class we know that water will always try to follow the path of least resistance, but when you're forced through 53 small holes your flow rate is going to hurt. 

The XSPC X2O Delta doesn't get away that easily either. The X2O Delta's densely packed copper pins have a detrimental effect. The end result is a loss in flow.

Flow analysis

Simulated Water-cooling loop
Let's see how the Alphacool NexXxos X2 Bold HIGHFLOW handled the increased heat-load of a quad-core...

Idle, Load and Overclocked temperatures
Ambient Temperature - 27.6 Deg C
Water Temp @ Idle - 33.8 Deg C
Water Temp @ Load - 34.3 Deg C
Water Temp @ OC - 38.1 Deg C

The Alphacool NexXxos X2 Bold HIGHFLOW handled the heat from the Intel Q6600 very well; considerably better than I had anticipated.

Now let's head over the page to see how the XSPC X2O Delta handles the heat...

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Testing Continued

Changing over waterblocks and running the same series of tests on the XSPC X2O Delta produced some interesting results which can be seen below:

XSPC X2O Delta Idle, Load and OC temperatures
Ambient Temperature - 31.5 Deg C
Water Temperature @ Idle - 35.5 Deg C
Water Temperature @ Load - 38.8 Deg C
Water Temperature @ OC - 41.2 Deg C

Unfortunately, due to Summer being just around the corner our temperatures are starting to soar significantly. The lack of thermostatically controlled room temperatures also means that ambient temperatures will not be able to be kept at the same for the duration of the review. A factor which becomes evident in the comparison between the Alphacool NexXxos X2 Bold and  the XSPC X2O Delta's results. Please remember that the graph below is purely for illustrative purposes only, and don't gauge the performance by the numbers shown.
Combination of Alphacool X2 Bold and XSPC X2O Delta results

However, if we average out the temperatures over the four cores and subtract the ambient temperature from the total we should arrive at our ΔT difference.

Alphacool NexXxos X2 Bold HIGHFLOW

ΔT Idle - 4.4 Deg C
ΔT Load - 16.4 Deg C
ΔT OC - 31.15 Deg C

XSPC X2O Delta

ΔT Idle - 3.0 Deg C
ΔT Load - 15.75 Deg C
ΔT OC - 31.5 Deg C

The Alphacool NexXxos X2 Bold manages to beat out the XSPC X2O Delta waterblock in the overclocking stakes, but comes in just behind for the idle and load testing. Now that we have analysed the Alphacool X2 Bold HIGHFLOW waterblocks performance, let's head over the page to see how the block perfomed as a whole in our conclusion...

Alphacool NexXxos X2 Bold Highflow water block Page: 6

The Alphacool NexXxos X2 Bold HIGHFLOW waterblock is a beautifully crafted piece of hardware and has certainly earned a place of pride in any high-end water-cooled rig. The quality finish and German engineered design features certainly help this waterblock to stand out  amongst the plethora of CPU waterblocks currently available on the market.

If you are looking for the best performing waterblock currently available, then the Alphacool NexXxos X2 Bold isn't quite the waterblock for you. But if you want a great looking all-round workhorse that is going to handle the heat-load of an overclocked processor more than admirably, then you could do well to look at the Alphacool NexXxos X2 Bold waterblock.

The move by Alphacool to not include a universal adaptor may pose a problem for those who regularly upgrade their system depending on the better performing platform at that time. This is further reinforced by the fact that AMD's Phenom processors are just around the corner and if you decided to purchase this waterblock now based on an Intel socket 775 based system, then you would need to re-purchase it again further down the track. Alphacool would be wise to look at investing in a universal attachment for their new range of CPU waterblocks.

Personally, I think the price is a little on the dear side of town, as it comes in slightly above the D-TEK FuZion. Dedicated Alphacool fans may overlook this.


The Alphacool NexXxos X2 Bold HIGHFLOW waterblock is available from SpecialTech for £ 40.99 , inc VAT 17.5%. By purchasing from one of our recommended retailers you can be sure that you will have a great experience and exceptional after-sales service.

The Good

Great Looks
Quality Build
Very respectable cooling performance for Quad-core
Relatively small footprint

The Mediocre

• Barbs not included
• Price
• No universal mounting

The Bad

• Nothing to report

Recommended award would like to thank SpecialTech for providing the product for review, and Chris from Alphacool for his assistance.

# Addendum: (5/11/2007)
In the light of the price difference between the D-TEK FuZion and the Alphacool NexXxos X2 Bold HIGHFLOW waterblock, Alphacool have adjusted their UK pricing to a very competitive £35.99 inc VAT 17.5%.

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