Closer Examination

At first glance, the Alphacool Eisblock XPX 1U is very similar-looking to the other Eisblock XPX water blocks, coming without a mounting bracket preinstalled and a top that houses a version of their recently developed cooling engine. This one has a black acetal top, which is the only version it comes in at this time, and does not support the add-on metal cover accessories the regular Eisblock XPX (non-Nylon) supports. There is an Alphacool logo on the bottom-right corner of the front, and the product name itself above, which I could have done without. There are also two BSP G1/4" threaded ports on top, with markings to indicate the preferred inlet and outlet directions. These ports are well threaded and spaced apart far enough to fit most large fittings easily, including 16 mm OD fittings.

The first indicator of something different is right here, with these two ports having flush mount G1/4" stop plugs out of the box. Going through the four sides reveals more ports for a total of three inlet and four outlet ports, and five stop plugs. You will need a flat head screwdriver to remove any of the stop plugs. The default configuration involves using an inlet and outlet port next to each other on the side, with these ports closer to each other than those above. A maximum of 13 mm OD fittings will work here unless you use low-profile, angled adapters first. Using these ports also means tubing is all from the side, which puts the profile of the installed block within the confines of a 1U server rack unit, hence the name.

Each side has a notch in the top, just where the pieces of the mounting bracket slide in and mate with each other above the cold plate. As seen above with the Intel bracket, for example, it is a secure fit, but you will have to get around the initial inclination, so be delicate as you have to press the pieces against each other hard to get them to overlap and stay secured. Once done, it looks more like any other Intel CPU block (or AMD with the AMD bracket) as it comes out of the box. Alphacool has implemented this mounting-bracket design across their CPU block generations, and it has the added benefit of increased customization in the form of optional color brackets that are sold separately.


Turning the block over, we see a large transparent sticker telling users to remove it prior to installation lest they inadvertently add a barrier against heat transfer. This sticker is used to protect the mirror finish given to the cold plate, which is very reflective. There is a slight convex bow to mate with a convex/flat CPU IHS, and the installation mechanism should provide for good contact in the center and all the way to the corners.


Disassembly (done after all tests were complete, of course) is fairly easy—unscrew the four screws on the base plate and it comes apart. The cold plate has 55.75 mm sides and is 3 mm thick, which is slightly more than most and decreases the rate of thermal transfer through it as a result. The jetplate is metal (stainless steel from what I can see) and 0.3 mm thick—again fairly thick, it will provide for a noticeable bow all things remaining equal. The thicker cold plate will resist it, however. We get the usual machined set of ultra-thin microfins and microchannels which are ~0.2 mm thick and ~2 mm tall. The microfins occupy an area of 32 x 34 mm, which is above average, and there are a lot of these at 81, so all other things being equal, liquid flow restriction should be higher, but the increased surface area will aid thermal transfer from the cold plate to the coolant.


Alphacool continues to use their patented ramp system here, although it is modified slightly to be able to fit in coolant flow from and out the side ports. The coolant enters a designated inlet port and is moved towards the center and up a ramp. Then, the coolant is accelerated through a Venturi chamber which also splits up the flow before it is moved through the jetplate. Alphacool's intention is to split flow up across a larger contact area on the microfins and microchannels. However, it is not convincing. Firstly, there is a mix of both coolant flow decrease and increase, and, secondly, even if the coolant is split up, it is still meeting the cold plate in the middle as with any other CPU block using a modern design. That having been said, there is an increase in the uniform distribution of coolant in terms of flow rate. Alphacool claims this will help produce more uniform and perhaps even above-average performance at lower coolant flow rates (0.3-0.6 GPM). The ramp system in this 1U unit is toned down to accommodate the extra side ports, so we will soon see how it performs.