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Les · 04-09-2002, 01:59 AM

Excellent work.
Have you you any indication of the cooling by secondary paths.Comparing* data from Insulated Simulated Die testing(95+% efficient heat transfer) with Thermal Diode CPU testing there is an indication that this may possibly be as high as 40% with a 100+w CPU.The secondary heat path issue and problems( as encountered by Billa**) with the constancy of the Thermal resistance of the Waterblock/Die(Transistor) interface are possibly the key to getting controlled repeatable conditions:
From your "Testing Coolers" presentation*** I have particular problems with this.:
"Thermal paste: To eliminate the first variable I simply changed thermal paste (initially I didn't want to waste the expensive stuff on testing!) from silicone-based to Arctic Silver II. This lowered the thermal resistance of the waterblock to 0.63oCW-1 - an improvement of just over 0.1oC. This figure allows an estimation of the thermal resistance of the interface between waterblock and transistor, knowing that AS II is about 10x the thermal conductivity of silicone based paste: Silicone paste ˜ 0.11oCW-1; AS II ˜ 0.01oCW-1. Note that these are approximate figures."
Surely for your load of 25w a change in thermal resistance from 0.74C/W to 0.63C/W should give a temp change of 2.75C and not 0.1C Alternatively the quoted "0.1C improvement" is equivalent to a reduction in thermal resistance of 0.004 C/W and gives,IF it is directly related to the TIM's thermal conductivity, waterblock/transistor interface resistance figures:- Silicone - 0.004C/W , AS II ~ 0.0004. For a similar size ASII interface(10mm x 10 mm ish) Billa** has been deternining Inconstant values from 0.16 - 0.2.3 C/W.

A note on the thermal impedance figures, presented by EMC2, for Thermagon products.:
e.g. T-Pli 210 @ 10PSI - 0.18 C-in^2/W ..... This translates to a thermal resistance of 1.16 C/W for a 10mm x 10mm die/transistor area .

* http://forum.oc-forums.com/vb/showth...threadid=75649
** http://forums.overclockers.com.au/sh...threadid=37515
*** http://www.cheese83.freeserve.co.uk/...ng/testing.htm

04-09-2002, 01:59 AM	#27
Les Cooling Savant Join Date: Oct 2001 Location: Wigan UK Posts: 929	Excellent work. Have you you any indication of the cooling by secondary paths.Comparing* data from Insulated Simulated Die testing(95+% efficient heat transfer) with Thermal Diode CPU testing there is an indication that this may possibly be as high as 40% with a 100+w CPU.The secondary heat path issue and problems( as encountered by Billa) with the constancy of the Thermal resistance of the Waterblock/Die(Transistor) interface are possibly the key to getting controlled repeatable conditions: From your "Testing Coolers" presentation* I have particular problems with this.: "Thermal paste: To eliminate the first variable I simply changed thermal paste (initially I didn't want to waste the expensive stuff on testing!) from silicone-based to Arctic Silver II. This lowered the thermal resistance of the waterblock to 0.63oCW-1 - an improvement of just over 0.1oC. This figure allows an estimation of the thermal resistance of the interface between waterblock and transistor, knowing that AS II is about 10x the thermal conductivity of silicone based paste: Silicone paste ˜ 0.11oCW-1; AS II ˜ 0.01oCW-1. Note that these are approximate figures." Surely for your load of 25w a change in thermal resistance from 0.74C/W to 0.63C/W should give a temp change of 2.75C and not 0.1C Alternatively the quoted "0.1C improvement" is equivalent to a reduction in thermal resistance of 0.004 C/W and gives,IF it is directly related to the TIM's thermal conductivity, waterblock/transistor interface resistance figures:- Silicone - 0.004C/W , AS II ~ 0.0004. For a similar size ASII interface(10mm x 10 mm ish) Billa** has been deternining Inconstant values from 0.16 - 0.2.3 C/W. A note on the thermal impedance figures, presented by EMC2, for Thermagon products.: e.g. T-Pli 210 @ 10PSI - 0.18 C-in^2/W ..... This translates to a thermal resistance of 1.16 C/W for a 10mm x 10mm die/transistor area . * http://forum.oc-forums.com/vb/showth...threadid=75649 http://forums.overclockers.com.au/sh...threadid=37515 * http://www.cheese83.freeserve.co.uk/...ng/testing.htm Last edited by Les; 04-09-2002 at 02:13 AM.