GTX 980 Water Block Round Up

Mounting Hardware

While all manufacturer’s included required mounting hardware, some manufacturer’s made errors.

– Alphacool included just enough screws, but some had paint filling the head meaning they could not be used

– EK included the wrong length screws for the backplate

– Swiftech forgot to include washers

Other complaints included the number of different types of mounting hardware – Swiftech had 6 types of screw in addition to multiple washers and nuts.

XSPC while keeping it simpler still expected you to place 10+ washers on the PCB and keep them in place while positioning a backplate on top of an unsecured PCB and block.

Alphacool also had hardware that was “soft” and easily stripped.

Compatability

On the R9-290x Block Roundup we found that the Alphacool was incompatible with Asus ROG motherboards in slot one.   This time they improved the design to cut out the areas that had issues and we had no issues fitting it.  It is however still beastly thick and may take up valuable space in a nearby PCIE slot.

Aqua Computer on the other hand went backwards.  Even the block without the optional backplate comes with a “mini” backplate that can interfere with some boards.  In addition the optional backplate is also a compatability concern by being so thick just as Alphacool was last time.  There was no additional hardware that would enable the block to be mounted without the “mini” backplate.

Flow Rate Testing

If you don’t know how to read a pressure/flow plot then check out our guide.  Testing was done by hooking up the block under test to a water faucet/tap and varying flow through it.  Flow was measured using a 5GPM King Instruments Rotameter, and pressure across the block was measured using a Dwyer differential manometer.  A Koolance CPU-380 block is also used here as a reference point:

My rule of thumb is that 1GPM at 1PSI is what I consider acceptable.  It can be seen that all but two of the blocks beat this somewhat arbitrary metric.  Alphacool’s block has the worst restriction by far.  At 1GPM it has over 4.5PSI of back pressure.  In other words adding this block in your loop *will* effect your flow rate negatively.  The cooling performance of your radiators might suffer and the cooling performance of your CPU block may also suffer.  The money you might save buying this may be necessary to apply towards a second pump in order to run it at a decent flow rate.

XSPC’s block is a small amount outside of our metric and is therefore disappointing but we wouldn’t say that it would cause a flow concern in the same way that the Alphacool block does.

The remainder of the blocks are very acceptable, with Bitspower being the lowest.

Onwards to thermal performance!