iXBT Labs - Computer Hardware in Detail






Coolers consumer qualities assessment

Second Edition

Detailed descriptions of cooling systems, thorough examinations of their technological features and operating abilities, multiple results of various tests are undoubtedly useful. But even after covering hundreds of reviews and looking through heaps of pictures users are often unable to choose a right cooler. 

Well, the common disadvantage of most reviews of PC coolers is lack of a general assessment of coolers' functionality and quality. Such assessment can come in handy in grouping all technical parameters and making an informative and comprehensive coolers characteristics table. Some sites do offer charts and ratings, but how such ratings are formed and what objective (subjective) parameters are accounted for is unclear. When poor-quality devices win and worthy ones lose, it is clear that the given approach is inapplicable. 

We decided not to give up and elaborated our own technique of integrated assessment of coolers consumer qualities. We do not consider it ideal but it reflects cooler's actual performance to a certain objectivity degree. 

So, here is the idea of the test technique. 

Any cooling system has 6 main characteristics to be estimated: 

  1. Thermal efficiency (or its reverse value - thermal resistance θja
  2. Noise level
  3. Technical quality of active components (fans, rotary pumps in liquid cooling systems etc.) - technical parameters, functionality and reliability 
  4. Technical quality of mounting mechanism - handy installation, fastener's technological effectiveness, its reliability and conformity to the norms 
  5. Technical quality of passive components (heatsinks, heat exchangers, pipe lines etc.) - technical parameters, technological perfection, reliability
  6. Professional aptitude degree - thermal effectiveness regarding processor groups a given cooler is meant for
  7. Price attractiveness (price effectiveness) - cooler cost and how this parameter relates to current economic realities

There are two bonus categories in addition to the above characteristics:

  1. Technological effectiveness (temperature control, fan failure alarm, power supply adapters/adjusters, protective mechanisms etc.)
  2. Accessories (thermal interfaces, power supply adapters, guides and descriptions, additional gadgets and devices) 

Fines can be imposed on a cooler in case of poor quality of any of its components, unsatisfactory serviceability or inadequate ergonomics. 

Each of the characteristics, except the professional aptitude degree, gets its own index calculated according to the established procedure. 

Thermal effectiveness

Eth = (WC*RFth)/TR (scores), 

Eth - thermal effectiveness index, WC - weighting coefficient, RFth - thermal reference factor (reference thermal resistance θja), TR - thermal resistance θja of a given cooler. 

Reference thermal resistance is 0.30°C/W for Socket 478 systems, 0.25°C/W for Socket A systems (the best values regarding the modern technological capabilities of mass production). The weighting coefficient equals 60.

Noise level

N = (WC*RFn)/NL (scores), 

N - noise index, WC - weighting coefficient, RFn - noise reference factor (reference noise level), NL - noise level of a given cooling system. 

Reference noise level is 25 dBA (typical background noise level indoors at night). Weighting coefficient is 60.

Active components technical quality (ACTQ) and mount technical quality (MTQ)

"Unsatisfactory" - 0 scores
"Satisfactory" - 5 scores
"Good" - 10 scores
"No complains" -15 scores

Any intermediate marks are also possible. For example, 14 scores can be interpreted as "the fan quality is excellent, but the power cables have too dull colors (the fastener is wonderful but its mirror surface doesn't properly reflect my face :)"; and score 1 can mean that "the fan quality is awful but it's still able to work a couple of works making a lot of noise".

Passive components technical quality (PCTQ)

"Unsatisfactory" - 0 scores
"Satisfactory" - 4 scores
"Good" - 7 scores
"No complains" -10 scores

Any intermediate marks are also possible.

Professional aptitude degree

Professional aptitude is determined by the professional aptitude group (PAG) which includes certain processors according to their thermal power. 

PAGs for Socket A processors: 

Professional aptitude groups Processor types
"A" (thermal power below 50 W)  AMD Duron under 1.2 GHz
AMD Athlon XP (ThoroughbredA, cpuid 680) under 1.6 GHz (1900+)
AMD Athlon under 1 GHz
"B" (thermal power up to 60 W)  all AMD Duron models
AMD Athlon XP (ThoroughbredA, cpuid 680) under 1.73 GHz (2100+)
AMD Athlon XP (ThoroughbredB, cpuid 681) under 1.73 GHz (2100+)
AMD Athlon XP (Palomino) under 1.4 GHz (1600+)
AMD Athlon under 1.2 GHz
"C" (thermal power up to 65 W)  all AMD Duron models
AMD Athlon XP (ThoroughbredA, cpuid 680) under 1.73 GHz (2100+)
AMD Athlon XP (ThoroughbredB, cpuid 681) under 1.8 GHz (2200+)
AMD Athlon XP (Palomino) under 1.53 GHz (1800+)
AMD Athlon under 1.3 GHz
"D" (thermal power up to 70 W)  all AMD Duron models
all Athlon XP models (ThoroughbredA, cpuid 680)
AMD Athlon XP (ThoroughbredB, cpuid 681) under 2.17 GHz (2700+)
AMD Athlon XP (Barton) under 2.08 GHz (2800+)
Athlon XP (Palomino) under 1.66 GHz (2000+)
all AMD Athlon models
"E" (thermal power up to 75 W)  all existing AMD processors

The following condition determines a professional aptitude group for a cooler:

Td =< 80°C, where Td = 40+(Phja), Td - processor core temperature, Ph - processor's maximum thermal power, θja - cooler's thermal resistance.

This condition results from the empirical capability of a processor to work at a technically acceptable core temperature (not over 80°C) in the rigid thermal internal mode (PC temperature 40°C and lower). 

Price attractiveness

Ep = (WC*RFp)/P (scores), 

Ep - price effectiveness index, WC - weighting coefficient, RFp - price reference factor (reference cost), P - average retail price of a given cooling system. 

The reference cost is 6 euros for forced air cooling systems (most coolers), 12 euros for improved coolers (equipped with hi-tech heatsinks), 35 euros for liquid cooling systems. The weighting coefficient is 60. The reference cost is fixed at 8 euros for the coolers of PAG "C" and "D". 


Professional aptitude group "E" - 10 scores
Professional aptitude group "D" - 5 scores
Proper temperature control - 5 scores
Fan failure alert - 5 scores
Preinstalled thermal interface (grease) - 5 scores
Preinstalled thermal interface (material with changeable phase state) - 2 scores
Power adapter (adjustable) - 5 scores
Thermal grease supplied - 3 scores
Additional installation tools - 5 scores
Others - 1 score


Professional aptitude group "A" - 10% off IAF
Noise level over 50 dBA - 15% off IAF
Low-quality passive components - all bonuses off, 20% off IA CCQ
Low-quality active components - all bonuses off, 25% off IA CCQ
Low-quality mount - all bonuses off, 25% off IA CCQ

All indices and bonuses are summed up after examination of each cooling system and brought into its "technical economical map". The sum of all indices and bonuses (with the deduction of fines) gives the desired integrated assessment of cooler consumer qualities (IA CCQ). If price attractiveness is not taken into account (for example, for estimation of pure cooler's functionality), a cooler is given an integrated assessment of cooler's functionality (IA CS). In the end, all obtained IA CCQ and IA CS form our Table of Ranks covering the economical and performance ratings. 

Well, I hope that the practical application of this new technique will help you in choosing the right cooling system which will meet the toughest requirements of quality and functionality. Comments and suggestions are welcome! 

Vitaly Krinitsin (vit@ixbt.com)

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