Welcome back to Extreme Rigs, today we will be reviewing the new “Summit EF X” CPU water block from Bitspower.  Just to confirm – this was initially called the GT X or GTX before being renamed shortly afterwards to the EF X.  It’s been a while since the last Bitspower block launched which was the similar “Summit EF” which we reviewed back in 2012.   With the Summit EF Bitspower offered a clean aesthetic and high flow rates but the thermal performance was lacking even when it was new.  Hopefully the Summit EF X will move the needle significantly as the EF runs 5-6C behind the competition.  A big thanks to Bitspower for supporting our testing efforts with a review sample:


Let’s take a look at the box.  As this was a pre release sample then it was worth bearing in mind that there may be slight differences with the final retail version.

Bitspower Summit EF X

The Summit EF X box is identical to the Summit EF box – in fact it even has a Summit EF sticker on it.  This is one thing we are going to assume will change.

Bitspower Summit GTX Box

The rear of the box has some useful mounting information which we are going to assume is the same for the new block as well as the old.

Removing the outer sleeve we get to the inner box:

Bitspower Summit EF X

Which upon opening gives another box with another Bitspower logo.

Bitspower Summit EF X

This small inner box contains the accessories as we will see later.  Spreading out the contents we also see the block itself and a backplate.

Bitspower Summit EF X

The backplate appears to be cast nylon:

Bitspower Summit EF X

Bitspower Summit EF X

As we are testing on X99/Socket 2011-3 we will not be using this backplate and instead mounting directly to the socket itself.

The accessory box contains instructions as well as a baggy of parts.

Bitspower Summit EF X

Instructions are hidden behind a spoiler:

Bitspower Summit "GT X" (sic) Instructions Provided at Release




Inside the baggy we see a replacement o-ring which we love.  Bitspower is the only company that does this and we’d like to see this more often.  An allen key for opening the block for service is also included.

Bitspower Summit EF X

The two bags of screws are the mounting nuts screws and springs:

Bitspower Summit EF X

Bitspower Summit EF X

Standoffs are provided for Socket 2011, while the screws are used in combination with the nuts and backplate for other intel sockets.  No washers are provided for the springs so the springs can scratch up the paint on the mounting bracket.

No TIM is provided.

The Summit EF X is wrapped in a sealed bubble wrap bag which is excellent:

Bitspower Summit EF X

Finally revealing itself we see that the Summit EF X has a beautifully machined and polished finish.  The bitspower logo is offset and personally I find it a bit more intrusive than the old style Summit EF logo.

Bitspower Summit EF X

Being a full metal block it of course has some weight to it and it feels strong and of high quality like other bitspower products.

Bitspower Summit EF X

In addition to this full metal version of the block there is of course a plexi/acrylic version:


And while we couldn’t find this gold version on Bitspower’s website, Performance PC’s is selling this one too:


One thing to note is that the screw threads are not complete turns for the full depth of the thread.  This weakens the threading and makes it more susceptible to stripping.  While this won’t be a problem on the metal version – users of a plastic topped version should bear this in mind and proceed with caution when adding fittings.

Bitspower Summit EF X

Having said this, this is not unusual in the industry and I’ve never really seen any complaints of thread stripping that weren’t really because of some janky fittings.

The finish is quite exceptional and on par with the best from Watercool and Aquacomputer.  It certainly feels better than the machining you get on EK’s and Koolance’s full nickel block.

Bitspower Summit EF X

The base is nickel plated too and protected with a clear plastic sticker which again we love:

Bitspower Summit EF X

This is a good thing and the finish is like a mirror:

Bitspower Summit EF X

Comparing to the old Summit block we see that the mounting bracket looks to be the same part, while the top appears to have been changed only it’s removal of the bolts from the face.  As mentioned before the logo is clearly more noticeable now.

Bitspower Summit EF XBitspower Summit EF XOverall the style updates Bitspower’s style while continuing the theme.  Think of it as evolution and not a CSQ style revolution.

The socket 2011 mount is again the same as the old block.  While this was good and unobtrusive at the time, the competition has again advanced and this mount isn’t the cleanest design out there.  We would like to see an update that avoids scratching the mounting bracket and is cleaner still.

Bitspower Summit EF X

Bitspower recommend screwing the nut down until the bolt is level with the nut.  You can go further and on the old Summit EF I definitely saw a slight improvement by doing so.  For our testing here though we will be following the manufacturer’s directions.

Bitspower Summit EF X


The feature list here is as described by Bitspower’s website and is pretty standard:

“**Design For 2017 Intel 7th-Gen CPU – Kaby Lake Series.

Features :
1. The Bitspower 2017 First CPU Water-Cooled Solution.
2. True Extreme-Flow Design.
3. With 0.3mm Fins / 0.3mm Channels.
4. Block TOP Cover Made of Hi-Quality Acrylic.
5. Block Base Made of Hi-Quality Copper C1100.
6. Compatible With Intel CPU **List Below .
7. RoHS Compliant.

Block TOP Color : Clear
Brackets Color : Matt Black
Dimension ( LxWxH ) : 95 x 95 x 18 MM

Thread : G1/4″ x 2

Bitspower CPU Water-Block Using the Following Processors :
1. INTEL LGA 775
2. INTEL LGA 1151(Kaby Lake) / 1150 / 1155 / 1156
3. INTEL LGA 1366
4. INTEL LGA 2011/2011-v3

Included :
1. Mounting Screw x 1Set.
2. Mounting Spring x 1Set.
3. CPU Backplane x 1PCS.”

So it’s interesting to note that it’s designed to be optimized for Kaby Lake, and not the 5820K Haswell-E that we will be using for test.  Clearly that should not be an advantage for it in our testing then.

For reference the port to port spacing is measured at a narrow ~26.5mm (centre to centre) which is identical to the old design.  This is borderline acceptable for fatter 3/4″ OD fittings depending on the brand, and larger quick disconnects will not fit.  It would have been relatively easy for Bitspower to grow this spacing even a few mm.

Enough of the outside – now let’s take a look inside the block.


To open the block up simply remove the 4 screws with the provided allen key wrench.  The screws are decently sized and there doesn’t feel like much risk of stripping anything.

Bitspower Summit EF X

Once the screws are out we can remove the cooling plate:

Bitspower Summit EF X

There is no jetplate here and instead a wide opening funnels the coolant into the centre of the cooling engine.  It’s noticeable how small the cooling engine is.  Most blocks use more of the available space.  Comparing to the older Summit EF we notice a few differences:

Bitspower Summit EF X

The top part of the block is indeed very similar.  There is no longer a jetplate, which makes sense given how wide the old jetplate was.  In fact I doubt the old jetplate was helping because a narrower opening is required to lead to some of the benefits of the jetplate like locally accelerated flow.   It’s also apparent just how much finer the channels are compared to the old Summit.  Those chunky channels have minimal surface area compared to the latest designs and it’s no surprise that the old design was falling behind.

Bitspower Summit EF X

The channels are evenly spaced and cleanly finished.  However if we compare to the class leading Alphacool block’s cooling engine shown below we can see that there is just a huge amount less surface area in terms of the total channel area, the depth of the channels and the number of channels.  Combine that with a lack of jetplate and expectations of high thermal performance are starting to wane.

Alphacool Eisblock XPX
Alphacool’s Class Leading Design

Bitspower’s design, like most is symmetrical in one axis and so we do expect it to have a preference in terms of mounting orientation.

But enough of expectations, it’s time to test!