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CPU Waterblock Comparison - February 2019

CPU Waterblock Comparison - February 2019 One of the most common questions I get asked as technical support for a watercooling retailer is, “Which CPU block should I get?”. As simple as this question may be to some of you, the answer isn’t always so straight forward for others. Which is precisely why I wanted to get my hands on as many as CPU blocks as I could and put them to the test! In total, I tested seven (7) blocks from five (5) different brands. I stuck purely to measurable performance metrics, as I really have a hard time quantifying any kind of aesthetic categories. So strap on your goggles and throw on some gloves, because we’re about get down to the technical details of my CPU block performance testing!



Before we begin talking about the results, we first have to talk about how I got this data. For starters, the specifications of the test bed platform can be found here, on Builds.gg.

  • The CPU is overclocked to 4.5ghz Core, 4.4ghz Cache @ 1.30v.
  • The ambient temperature was measured with a digital thermometer located next to the test bench system.
  • The CPU temperatures were calculated by taking the average of the “average CPU temperature” for all six (6) cores.
  • For “Full Load” testing I ran Asus RealBench Stress Test for one (1) hour.
  • Idle temperatures were recorded after the system had been “idling” for a minimum of 30 minutes.
  • Thermal Grizzly Kryonaut was used for each block, and was applied with the same method each time.
  • The coolant in the loop was distilled water with 2 drops of Mayhems Biocide and Inhibitor each.
  • The custom loop included a 240mm (60mm thick) TFC X Changer radiator equipped with two (2) 120mm Corsair ML120’s controlled by an Aquaero 5XT (the same fan curve was used for all blocks).
  • Coolant temperature and flow rate were also monitored using an Aquacomputer flow sensor and in line temperature sensor connected to the Aquaero.
  • Each block had all the proper jet plates/inserts for X99/X299 installed prior to testing, if they had any.
  • Every block was mounted using its proper mounting hardware for the X99/X299 platform.
  • Each block was orientated with the ports vertically, with the “In” port being below the “out” port on the directional blocks.




  • Each block was put through a number of tests, and multiple aspects of performance were measured. The following blocks were tested:
  • EKWB - Velocity Nickel/Plexi
  • EKWB - Supremacy EVO Nickel/Plexi
  • Thermaltake W4 RGB
  • Heatkiller Pro IV Nickel/Acetal
  • Barrow Intel X99 Nickel RGB
  • Bitspower Summit EFX
  • Bitspower Summit ELXZ
  • Below I will outline the results of each testing scenario.


Full load tests

As seen in the graph shown below, the clear winner of the “Full Load” test was the Heatkiller Pro IV. It led the Barrow Intel X99 block by with a very narrow margin of 1.66°C. The rest of the blocks stack up even closer, with barely more than 1°C between them until you get to the final two blocks on the right hand side. Some may take one look at this and say that the Heatkiller Pro IV is the block for them, however, if you look a little closer, you’ll see that the delta between the entire set of blocks is only 5.76°C.

At the end of the day, 6°C is rarely going to make or break an overclock, and it won’t ever make a noticeable difference in the CPU’s lifespan. You can look at the numbers however you’d like, but I’m still going to stick to “use whatever block you like the look of most” - because performance wise, it really doesn’t make a difference.



Idle tests

Personally, I’m not a huge fan of idle performance of any system. The definition of a PC “idling” is a very loose definition, at that. Nonetheless, I still recorded the “idle” performance of every block in this test. You can see how they line up in the graph below. Oddly enough, the Heatkiller Pro IV did not keep its title as the “coolest” block for this test. Instead it was beat out by the Thermaltake W4 RGB block, along with two others. The only block that actually scored consistently between the “Full load” and “Idle” tests was the Bitspower Summit EFX, and it ranked dead last in both… the engineer in me still appreciates Bitspower’s consistency here though!



Flow rates

Testing the flow rate of each block was one aspect that I was very excited about. The Aquaero and Aquacomputer sensors made this extremely easy… correlating the data with the rest of the numbers that were gathered wasn’t nearly as simple. As you can see in the graph below, starting on the left hand side, the EK - Supremacy EVO had the lowest flow rate by far. However, if you take a look back at either the “Full Load” or “Idle” graphs, you will see that the Supremacy isn’t ever the worst performer.

This correlation, or lack thereof, leads me to believe that the flow rate of a block does not impact the performance as greatly as other factors. Perhaps taking a closer look at fin density and cold plate design could lead to more correlations between the performance of the block, than flow rate. At the end of the day, flow rate is one of the last metrics I would use to pick a CPU block for my custom loop.




This is probably the metric some of you care most about. The “budget kings and queens” out there will really appreciate what Barrow brought to the table in this lineup of blocks. The prices of these blocks in USD, on Performance-PCs.com, are as follo-ws (blocks offered in multiple platform styles at the same price are listed as well):

  • Barrow Intel X99/X299 RGB (AM4,115X) - $26.95
  • Bitspower Summit ELXZ - $46.95
  • Thermaltake W4 RGB - $69.99
  • Bitspower Summit EFX (AM4) - $72.95
  • Heatkiller Pro IV (AM4) - $80.95
  • EK - Supremacy EVO NP (AM4) - $84.99
  • EK - Velocity NP (AM4) - $84.99

As you can easily tell, Barrow was bound to win this test right out of the gate being that their price point is so incredibly low. So if that’s all you were after with this review, then you don’t have to read any further! At $0.42/°C, none of the other contenders even come close to matching Barrow’s price to performance. It’s somewhat difficult to correlate the rest of the data from this metric to the rest of the tests, but for the enthusiasts out there, you can appreciate that you don’t have to pay “top dollar” for the best performance. Watercool’s Heatkiller Pro IV block ranks 5th on the price to performance graph, but tops the chart for “Full load” performance. It was really nice to see that the very humbly priced Bitspower Summit ELXZ ranked second in this line up, and still held its weight throughout the other performance tests. Overall, if you’re on a budget go with Barrow. For the rest of you, decide if aesthetics or performance are what matter to you more.




If you came into this blog expecting to find a clear cut answer to the question I posed at the very beginning, I apologize, as I’m afraid it’s still just as user dependant as before. Although my testing did tally up these blocks performance, and rank them accordingly, I still can’t say that one of these blocks is the clear cut winner for all end users out there. Each block seemed to bring something different to the bench.

If all your after is top tier performance, you probably know which block is right for you. If you’re working with a tight wallet, there’s options for you as well, but for the rest of us we all still have to shop around for the block that really catches our eye. I hope that at the very least this brought some peace of mind to you, as picking out your custom loop components should be something you enjoy. Rest assured that most any block you pick up from Performance-PCs will perform well.


I do hope to take these tests even further with even more CPU blocks as well as other hardware platforms, so stay tuned for a Round 2! Check out the video for this blog here.

I can’t forget to mention all of the brands that helped out and supplied me with their blocks. Thank you EKWB, Thermaltake and Watercool for sending me your gear to play with!


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