Hydrocool Hydro-Stream Waterblock – HS5

Waterblock Test – Joe

SUMMARY: Excellent performance, but needs a high power waterpump to shine.


The good guys at Hydrocool PTY Ltd were nice enough to send a Hydro-Stream waterblock to test – this is the HS5 version, which is the version with the highest pressure drop; the HS3 version is less so. (Note: Hydrocool PTY is an Australian based company and is NOT associated with Corsair Hydrocool).

The Hydro-Stream features

  • Polycarbonate connectors for ½” ID tubing
  • 100% pure silver base
  • Micro-channel copper interior
  • Polycarbonate top with color options
  • Quick and easy mounting clip

The mounting clip is a sheer joy – simply slip it over the socket’s lugs, rotate the lever and it’s securely in place; mounting pressure is centered over the CPU’s core, where it should be.

Inside the waterblock are small copper channels which are affixed to the silver base plate; the channels are closely packed and hence result in a high pressure drop. The large surface area does help performance quite a bit, as shown below.

The one concern I have in any waterblock that uses tightly constrained interior spacing is the possibility of clogging – adding a filter to a watercooling system will keep thing clear but can add substantially to the system’s pressure drop (alternative: place the filter on a separate loop powered by another pump).

The base is silver…


and quite thin – 0.5mm according to Hydrcool’s specs.


The Hydro-Stream was tested using the CPU Die Simulator and Waterblock Test Rig.


Test Conditions: Inlet Water Temp: 28.5 C; Mounting force: 15 pounds; Heat Load: 70 Watts.




Pressure Drop – psi

Pressure Drop – inches H2O





NOTE: These results are NOT comparable to tests done by others.
Unrounded data: 0.122 C/W with 0.0011 std dev.

Test Results indicate that the Hydro-Stream’s pressure drop (or head loss) across the waterblock is very high; resistance such as this means that Hydro-Stream needs a hefty waterpump to extract maximum performance, especially if other components in the system are restrictive.

I found that performance degraded by about 0.8ºC at a flow rate of 0.5 gpm and by an additional 0.4C at 0.3 gpm; I could not get a reading above 1 gpm as my test rig could not overcome the pressure drop above 1 gpm. Note that even at severely reduced flow rates, this waterblock performs quite well compared to others. Literature supplied by Hydrocool clearly states that the there is “Not much performance benefit [of waterflow rates] above 2L/min”.

For a comparison of the Hydro-Stream’s performance to other waterblocks tested to date, see Overclockers.com Waterblock Test Results.


The Hydro-Stream HS5 Waterblock is an excellent choice for CPU cooling, with the proviso that a large waterpump will be required for best performance, as long as other components do not unduly restrict waterflow.

Thanks again to Hydrocool PTY Ltd for sending this our way.

Email Joe

Be the first to comment

Leave a Reply