Liquid Flow Restriction

I use a Swiftech MCP50X pump with a FrozenQ 400mL cylindrical reservoir. The pump is powered through a direct SATA connection to an EVGA 1300G2 PSU and controlled by an Aquacomputer Aquaero 6 XT. There is a previously calibrated in-line flow meter and Dwyer 490 Series 1 wet-wet manometer to measure the pressure drop of the component being tested. Every component is connected to the manometer by the way of 1/2" x 3/4" tubing, compression fittings, and two T-fittings.


Since there are only two blocks being compared here, I added some more items for context, including an "average" GPU block of the GTX 1080 for the many more blocks I have tested. The general trend is that these two GPU blocks are less restrictive than your average CPU block that includes many more and often thinner microfins and channels that restrict coolant flow. The EK block is slightly less restrictive, which could be because of the split central-inlet flow, as well as other factors, including the different number of microfins, thickness of said fins, and so on.

Thermal Performance

Test System

Test Methodology

Testing a block for thermal performance is fairly simple once you realize that you have to measure VRM temperatures manually. As such, I installed an Omega NTC type thermistor on the bottom VRM and connected it to an external display for a VRM temperature readout, which may inflate the actual values slightly. TechPowerUp GPU-Z was used to monitor GPU core temperatures. The GPU was overclocked to 2 GHz using MSI Afterburner, although with the nature of GPU Boost more dependent on the power limit when it comes to NVIDIA's Turing microarchitecture, it did vary ever so slightly as well.

Everything required was placed inside a hotbox, and the ambient temperature was set to 25 °C. Three separate mounts/runs were done for statistical accuracy and to remove any mounting-related anomalies. For each run, a 30 minute Unigine Heaven 4.0 run was done, and temperatures were monitored until a steady state was reached, after which they were recorded. A delta T of GPU core/VRM and loop temperatures was thus calculated for each run, and the average delta T that was then obtained across all five runs. This way, the cooling solution is taken out of the picture.

Test Results

The absolute temperatures achieved were really good for both water blocks, and within half a °C for both tests. The EK block did fare better—another small victory added to the even smaller one with VRM temperatures. This could be the result of the CORSAIR backplate potentially having an air gap between it and the PCB owing to the lack of VRM thermal pads on the back, but it is only a hypothesis not backed by empirical evidence. CORSAIR clearly did not think it worth adding thermal pads here and chose to bundle in the backplate instead.