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First off, thanks to the Water-Cooling Shop for providing the NexXxoS HP Pro for review. The block is very new to the UK, with only very few blocks having been imported for sale from Germany. If you want one for yourself, head on over there right away.

Last year I made my initial venture into the world of watercooling when h2o-computer sent me their "Cool Sprinter" watercooling kit. At this early point in the review I'd like to bring up my grammatical confusion related to "watercooling" or "water cooling", as with "watercooled" and "water cooled". Which is correct I have no idea... in any account, I'll be using the single word form. My first foray into watercooling helped me overcome the fear of mixing water with electronics and since then my primary rig has been watercooled 24 hours a day. Until a short while ago I was still using the block from the Cool Sprinter kit but now I've been sent this Alphacool NexXxoS HP Pro block by the lovely folk at water-cooling.com. Until quite recently the NexXxoS HP Pro (HP Pro from now on) was top of the rankings at watercoolplanet but has since been topped (by a tiny margin) by a different block. We can still assume that this should be one the top performing designs of block around at the moment, let's see if it lives up to it's hype and potential.

The first thing I did when I received the block, and the first thing I will do in this review, is have a long hard look at the quality and construction of the block. I've been quite picture heavy as I believe you really need a decent look at the build quality of a waterblock. A waterblock made badly could result in catastrophe such as a leak, or less dramatically result in poor contact leading to lacklustre cooling.

We see the block is made up of a rather thin copper plate base topped with a 10mm thick acrylic piece which also acts as the hold-down for the block to the motherboard. The base has a rather odd design, with a pin-like maze through which the water flows on the inward stream. The output is via a more traditional channel cut round to the "top" of the block. We'd better also have a look at the included extras - the four securing bolts and the nylon washers and bolts used with them, four springs and four "thumb bolts" for tensioning the block, and finally a fairly bog-standard sachet of thermal goop. It might have been nice with a block of this price (and hopefully quality) to recieve a higher quality thermal grease such as a small tube of arctic silver or similar.

The finish on the base of the block matches up to the quality of the top side and then some. Oftentimes people, when buying heatsinks and blocks, feel the need to "lap" the base to improve the finish to a polished shine to, in theory at least, increase the thermal conductivity (and hence the performance of the cooler). Have a look at my review of the lapping kit available from Kustom if you want to know a little more about the lapping process. Thanks to the protective layer attached to the HP Pro and the excellent job that has clearly been done on the base there is certainly no need for lapping in this case. Full marks to alphacool for doing a great job of this often overlooked process. Hopefully the following pictures will do the finish justice. Note the 2500+ Barton which will be used in the temperature testing later on.

As is hopefully evident the HP Pro has quite a striking appearance. Whilst that might seem wholly unimportant, a lot of watercooling setups have looks as a large factor - you'll generally find watercooling setups installed in the more "elaborate" cases so the block, the central part of the system, has to look good. The HP Pro definately passes this test.

The HP Pro's acrylic top measures approximately 75x60x10mm. The copper base is a 50mm square and approximately 2mm thick. The block attaches to your motherboard not using the more traditional three-lug socket clips but rather via four bolts through the nearly-standard mounting holes found on most Athlon platform motherboards. To display to you the method for mounting the HP Pro here are, guess what, some more pictures. Note that I have cut a hole in the motherboard tray of my PC60 to ease the process of attaching the bolts - normally one would need to remove the motherboard from the case or tray to carry this out.

Here you see how the bolts are attached to the motherboard itself meaning the HP Pro doesn't need to rely on the plastic clips on the CPU socket. It's not a particularly heavy block so the use of the bolt-method may seem a little over the top but it will have running water passing through which this will increase it's weight somewhat. I would warrant the main reason for the use of the mounting holes is for security - it's much safer to move a machine around when the block, or even heatsink, is secured in this manner. Bear in mind that a version using the cpu socket lugs is also available.

After that it's a simple case of sliding the block down over the bolts, dropping on the supplied springs and then hand tightening with the large securing nuts. The tightening is not an exact science, you will need to use some common sense when clamping the block down. However as long as you stick to using your fingers and not pliers or some other tool, tightening until the nuts feel fairly tight will provide a decent bond. Make sure the block doesn't move around if you give it a nudge, and also be sure to tighten the four bolts equally. My preferred method is to fasten two opposing corners fairly loosely, then the other two, then tighten each bolt in turn a few twists at a time. This will help keep the block fairly level on the core as you tighten down onto it and prevent any nasty crushing accidents.

You may have noticed in the early pictures the spray-type nozzle inside the central port on the block top, spraying in the water above the maze in the copper block. Note that this definitely needs to be used as the in-flow for the block due to this nozzle. I mistakedly connected it up the wrong way round the first time I installed it, I am a little ashamed to admit. I was bemused by the huge amounts of turbelence, in fact froth, in the tubes until I realised what I had done. Hopefully you can learn from my mistakes, or just laugh at my idiosy... either is fine with me.

After connecting the block up the right way around I set about testing it's performance. The platform I used for testing the HP Pro was a 2500+ Barton processor running on a KT400A based AOpen AK77-400MAX motherboard. The board has a passive northbridge sink which means for fairly high sensor temperatures, especially when used without a fan-driven heatsink on the CPU (which sends some air the northbridge's way). The case used is a lian li pc60 although the tests were run with the chassis open to the air since I'm still working on some modifications to the side panel. The water loop consists of the HP Pro (obviously), an innovatek block on the radeon 9800AIW card, an AquaTube reservoir mounted to the top of the case and an h2o-computer 1x120mm radiator also mounted at the top of the case. The pump used is an Eheim 1046, a very common pump and one the majority of people running 3/8" or 8/10mm systems will use.

Alphacool NexXxoS HP Pro

I ran the cpu at stock (~1830MHz) initially to check the temperatures under normal conditions. Results were obtained using the wonderful Mother Board Monitor. The first result is the AthlonXP 2500+ running at stock speed and stock voltage. After that is the CPU at stock speed but at 1.85V (maximum for this board).

HP Pro, 1.65V, 1.827GHz, idle	HP Pro, 1.85V, 1.827GHz, idle

Fairly impressive temperatures I would say bearing in mind the only fans running in the system were the 120mm fan on the radiator (at between 5 and 7 volts) and the 140mm (yep!) fan in the power supply (at "low" speed, approx 7V at best guess). Loaded to full (using Prime95) the temperatures change as below:

HP Pro, 1.65V, 1.827GHz, load	HP Pro, 1.85V, 1.827GHz, load

Next I ramped up the speed, staying at 1.85V. Temperatures stayed pretty respectable...

HP Pro, 1.85V, 2.162GHz, idle	HP Pro, 1.85V, 2.328GHz, idle

... and here's the readings when fully loaded at fully overclocked speed:

HP Pro, 1.85V, 2.328GHz, load

Innovatek innovaCOOL

I replaced the HP Pro with my innovatek innovaCOOL block for comparison. I would also have tested against the block from the h2o-computer set but I, unfortunately, managed to crack the acrylic top when swapping out the 6/8 fittings for 8/10 ones. Marvellous. Let that be a lesson to be careful when screwing in barbs, especially since the HP Pro comes with no barbs pre-attached (unless the lovely people at water-cooling.com attach the ones you order, mine came separately). The innovatek didnt perform quite as well, but the differences are less than earth-shattering. We're still at 1.85V for these tests:

Inno, 1.85V, 2.165GHz, idle	Inno, 1.85V, 2.328GHz, idle

Here's the innovatek on the fully loaded overclocked CPU:

Inno, 1.85V, 2.328GHz, load

These results are better demonstrated by the following graphs:

NexXxoS block

Innovacool block

Comparison

Apparently from these results the HP Pro outperforms the innovacool block. Temperatures are pretty respectable all round. The HP Pro was much cooler at stock idle and I got my hopes up rather. When overclocked and loaded however, the gap closes and is quite tight at full speed and load. The innovatek block must perform better under heavy load for some reason - this might be due to the rather thin copper base on the NexXxoS as opposed to quite a chunky core inside the innovatek (no picture sorry, it's a sealed unit as far as I can tell). The very thin copper block would mean quick heat exchanging but little scope for holding heat (thus smoothing things out when there's more heat being produced). Perhaps a thicker base would have benefitted the HP Pro?

It has been suggested to me that the rest of my loop may be "to blame" for the closer temperatures at high load. Paulus, who sent the block over, said that perhaps the radiator may be an inhibiting factor, not capable of dissipating the heat any faster. This seems feasible, and I'm willing to accept it as the reason... however I do have a fairly standard radiator - I think most people run a single 120mm rad like mine - so it seems perhaps the HP Pro would be more suited to a larger radiator to get optimal results. I guess that would be true of almost any block.

I wasn't sure what to expect with the HP Pro. I didn't want to have too high hopes since I was slightly disappointed last time with watercooling. What I have no doubt about is that the HP Pro really looks the part. It's aesthetic design has clearly been taken rather seriously by the people at Alphacool and the build quality certainly meets the quality of design work. As for the internal design of the block, the rather unconventional maze work, the jury is still out. The temperatures attained during the review suggest the block performs pretty well but I have been witness to many forum debates over the design of the water channels within this block. Many suggest a dual outlet design would be more efficient, others suggest the design should be completely rethought.

Final thoughts

It was hard to tell what the design did to waterflow... one thing I did notice about the central maze, though, is that it's quite effective at collecting what I can only refer to as "crap". After running it for a week or so I noticed some strange residue in the core. I'm not sure whether it's from the pump or the water or the additive or what, but most of it cleaned off under running water.

Aside from that slight niggle, which I don't see as being a major problem, I've been pretty happy with the HP Pro. The installation is very simple (once the bolts are installed) and secure, and once in place looks great. The performance outdid my innovacool block by a reasonable margin and is by all accounts rather decent.

At £35 the HP Pro is more expensive than most standard heatsinks (and of course requires that you have shelled out for the rest of a watercooling circuit). As waterblock prices go it's not too outlandish, and the quality and appearance of the block help to satisfy the price premium.

I've certainly taken a shine to Alphacool products, in the hope (or expectation) that they are all as well made as the HP Pro.

Good performance
Great looks (I know, I know.. but it matters!)
Build quality very high
Very well lapped base
Easy and secure installation
Choose your own tubing connectors (since no defaults are included)*
Not cheap
Somewhat "controversial" maze design
- can get clogged
No barbs included (extra to pay, risk during installation)*

* shown here as both a pro and con, since it has both good and bad repercussions.

Related:
shop.water-cooling.com.
Alphacool product range.
Alphacool website.
Watercoolplanet block rankings.