Alphacool OTC Flat 8800 Water Block

Testing Methodology

Testing Methodology

For the testing phase of the review I have chosen to test the Alphacool OTC Flat against another well known water-cooling block - the EK FC8800GTS. A Laing DDC Pro pump with OCLabs alternative top will be used to assist in making a comparison. I shall be looking specifically at pressure drop, flow resistance and cooling performance from within a water-cooling loop. All tests will be run 3 times to ensure the elimination of any oddities. I have included the setup details below:

Pressure Drop

For the pressure drop test I used a 25L portable water container filled with 20 litres of water, with a 1/2" plastic threaded barb placed in the bottom to represent the reservoir. A stop tap was inserted immediately after the 1/2" barb to allow for a faster water-block change. The True-Flow pressure meter was used to record the head pressure per 1 minute testing cycle. The pump was primed and let run for a short period to ensure that no air bubbles were left in the loop. The water was allowed to run back into the container after passing through the pressure meter meter via a 'T' connector in order to minimise wasted time between water block changes.

The first run made was with only the pump and pressure meter included in the loop and the water pressure noted. Then for second run the Alphacool OTC Flat water block was included into the loop and the drop in loop pressure recorded. The same procedure will be followed for the EK FC8800GTS water block.

* 1 x Laing DDC Pro pump with OCLabs alternative top @ 12v
* 1 x Alphacool OTC Flat and EK FC8800GTS water block
* 1 x Powertech variable DC power supply (quoted accuracy /- 0.2V)
* 1 x Multi-meter
* 25L portable water container
* 1 x Glycerine filled True-Flow pressure meter. (kPa/psi)
* 1/2" ID XSPC tubing
* 1/2" barbs
* 2 x stop-tap fittings

Variable PSU Pressure drop testing
EK FC8800GTS pressure test


In a similar test to the pressure drop testing above, the flow test will highlight just how much the water blocks restrict the natural flow of the watercooling loop. Utilising a very simple setup consisting of a pump, I/2" ID tubing, water blocks, bucket and a stopwatch we will see how far removed from the absolute flow of the pump, that the water blocks hinder flow. Running the pump into the bucket for one minute and then measuring the amount of water pumped will be the 'absolute flow' of the pump.

To calculate the flow-loss or restriction of each water block, they will each be included into the loop (one at a time) and the same procedure followed. The flow rate will be recorded in Litres/ hour. All simulations will be run 3 times each to ensure uniformity of the results and an average then taken.

Assessing flow

Loop Simulation and cooling performance

I have decided to impliment a control setup for the testing phase of this review. In doing so I have replicated a watercooling loop similar to that in conventional water cooled setups, but it will include the GPU alone and should return consistant and unbiased performance results. The open loop that I have chosen to run with should give quite a good indication of how the Alphacool OTC Flat water block would perform in your system. The Alphacool OTC Flat's performance will be assessed at the Laing DDC Pro's operating voltage of 12 volts. For each seperate run, the pump was allowed to run for 20 mins to ensure the evacuation of all air from within the loop. The temperatures were taken at 30 minute intervals to allow them to 'settle'. RTHDRIBL will be used in order to simulate graphic load. Due to low maximum resolution of my CRT monitor, RTHDRIBL will be run at 1280 x 960...whilst it isn't perfect for stressing the graphics card totally it should still give some comparitive results.

I have recorded temperatures at idle, load and and an overclocked loaded state; all GPU related temperatures will be taken using RivaTuner vers 2.06 and water/ambient temperatures were taken using a common household mercury thermometer. The mercury thermometer was allowed 5 minutes to aclimatise to air and water and then the temperature recorded. The setup used has been included below:

* 1 x Laing DDC Pro pump with OCLabs alternative top @ 12v
* 1 x Alphacool OTC Flat and EK FC8800GTS water blocks
* 1 x Powertech variable DC power supply (quoted accuracy /- 0.2V)
* 1 x Multi-meter
* 1 x Tribal Overkill reservoir
* 1 x Toyota Camry heater core
* 1 x Scythe Minebea 120mm cooling fan
* 1/2" ID XSPC tubing
* 1/2" barbs.
* 1 x Intel Q6600 processor
* 1 x ASUS P5B Deluxe wifi/App motherboard (bios version 1101)
* 1 x ASUS EN8800GTS graphics card (640Mb version)
* 2GB Corsair XMS2 PC2-6400 RAM
* Antec NEO EarthWatts 500W PSU
* 80 GB Western Digital SATA II HDD

Loop simulation

Please follow with me over the page to see the test results...
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Most Recent Comments

02-12-2007, 13:43:02

Great well written review Peevs. I have been wondering how these will fair and in the very least they are an attractive solution offering a bit of choice. Bit of a shame about the overall performance but looks like I'll be happy with my EK block Quote

02-12-2007, 13:57:54

I like the idea of this block tbh. Looks just so much nicer than the usual fat-topped ones. And for its size (or lack of), doesn't perform too badly.

Nice job Mr Pvs.Quote

02-12-2007, 19:01:47

Thanks guys, the feedback is appreciated. I'm glad you found the review a good read. Quote

02-12-2007, 19:05:56

I can't believe how thin it is!

Kinda disappointing about the conclusion, but that doesn't bother me as I bought the EK Quote

02-12-2007, 19:46:07

Got flow?

Good review Peeves Quote

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