Thermalright XWB-01 Waterblock Review

The Thermalright XWB-01 is designed for all Intel 775 and Athlon64 processors provided the watercooling setup is plumbed for 1/2” ID hoses.  Here is an overview of the system and testing methodology.

DFI the LANParty UT 680i LT
Pentium Core 2 Duo E6400 running at 2.13Ghz
Thermalright XBW-01
Danger Den TDX

The watercooling system consisted of a Hydor L35 pump, Black Ice Extreme radiator, Sunon 120mmx 35mm fan (running 12v), and a small reservoir for water storage and air collection. 1/2" I.D. hose was used throughout with minimum hose lengths used whenever possible.

Smart Guardian was used to obtain and record system temperature data and being that this is a dual core processor we needed to activate both cores to generate some good heat.  We used a program called Stress Prime to provide processor usage.  Stress Prime is a front end to Prime95 that allows you to run 2 Prime95 instances at the same time.

Editors note: Even though the Windows XP task manager reported 100% processor usage we could never attain a 100% of the rated heat output as documented by Intel (see below) when using Stress Prime (Prime95) as a basis for that heat production. Knowing this the program was run until the maximum temperature was attainted and stabilized.

Other things to consider when judging software induced heat output.
a) Clock throttling by the processor at high temperatures.
b) Normal software isn't designed to produce maximum heat output.
c) Variances of cooling temperature.
d) Variances in CPU load.
e) Inaccuracies in thermal diode readouts.
Of course the list goes on..

Our testing methodology is aimed to provide a real world look into this waterblock given the test system provided.

A C/W rating for these results can quickly be calculated using this formula.

C/W = (CPU temp - Ambient temp)/(Variance(%) * CPU Watts)
Allowed variance for this test = 80%
CPU Watts = 65W

0.53 C/W = (50C - 22.5C)/(.8(65W))

To calculate a new C/W rating for this test we will need to factor in the increased processor wattage. The formula and constants for this are listed below.

ocC/W = dCPU Watts * (ocMhz / dMhz) * (ocVcore / dVcore)2
ocMhz = 3200
dMhz = 2130
ocVcore = 1.36
dVcore = 1.2
The variance still applies for our C/W calculation
Allowed variance for this test = 80%
CPU Watts = 124.8W

0.35 C/W = (57C - 22.5C)/(.8(124.8W))

In our heatsink and waterblock tests we don't really focus on overall load temperatures but rather how well the product can remove heat given a specified heat load. Since this is a real world testing method we need to take into consideration real world variables and estimate tolerances. This is why we normally only apply 80% of the total wattage output to our heat calculations.

The resulting C/W number is used to rate how efficient a heatsink or waterblock is based on the given heat load. These numbers can then be used to determine heat capacity, the larger the difference the less efficient the waterblock is. (aka not good for overclocking)

To our surprise the XWB-01 won both of our heat tests (stock and overclocked) by a noticeable margin.  We suspect this is due in part to the increased surface area the microfin design provides and not flow rate. 

You see the XWB-01 is rather restrictive in terms of water flow.  Normally with high flow waterblocks a powerful whirlpool will form in our res as water goes back to the radiator however with the XWB-01 the whirlpool did not form and brought into question if our L35 was actually pumping anything.

Keep in mind these calculations are provided for demonstration purposes only and may not reflect the actual lab tested C/W rating, but we feel we're pretty close