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Best heatsink/Overclockers.com database units flawed?

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markst1

Registered
Joined
Jan 22, 2002
Overclockers.com has an extensive heatsink database listing the top heatsinks in order of C/W units and the links to the data. Unfortunately the correct unit for evaluating a heat sink is NOT C/W,it is C/W/CFM. You can use a crappy heatsink with a powerful high CFM fan and it looks good. So I took all the data from the links and recalculated to obtain C/W/CFM units. The Volcano7+ heatsink calculates to be the best heatsink on the market. The MCX4000,and AVC Sunflower are next. So I got the Volcano7+ and removed the intolerably noisy 70mm fan and replaced it with a 120mm fan and modified a fan adapter to make it fit. Now I run my [email protected]+Ghz cool almost silently. Comment?...Mark
 

Tipycol

Member
Joined
Aug 20, 2002
Does the CFM part really matter since most of the top heatsinks use the same fan anyway?
 

MILLTHERM

Registered
Joined
Aug 3, 2001
Unfortunately CFM's as a constant for comparison do not work. Each sink has a pressure drop so a sink like the AX7 performs at around 80% freeflow, other sinks like the ALPhA,volcano and swftechs with higher fin densities run 40 to 50% of the freeflow value. The traDE OFF HERE BEING(capsoff) increased velocity rather than airflow volume -overall dynamic energy (velocity+cfm) would give a better picture from a design point of view but is really useless for comparison purposes

A better constant is noise vs thermal performance. In that kind of a comparison if you tested all the sinks at say 40 dBA most would fall within a degree C of each other. So by that criteria the VANTAC on the front page would seem to beat the grouping of the other sinks.....

EFF. in the overclocked world has little to do with overclockers interests, they as a rule desire the best performance. A heat sink with a small form factor and a small fan may dissapate more heat per cubic inch and be 2X more eff. than any other sink but if it does not get the overclock it will not be noted.

Water cooling, heat sinks with large over speed fans and their associated noise dominate while being the least elegant of the solutions available.
 

CrystalMethod

Senior Band Wagon Jumper
Joined
Jun 9, 2001
Location
Montreal, Quebec, Canada
The data base tests unit's as they are packaged. As far as I know the only modifications Joe has ever done is lapping the heatsink, and/or replacing the fan with the same size but a higher CFM fan. It would take forever for him to test with all combinations of fans, on top of modifying them to fit. You would have to retest all the heatsinks with your fan and adapter to see how much off the database actually is. The database is a reference, not an absolute. Not everyone is willing to hang an all copper heatsink and 120mm fan off their socket lugs (as would be the case for socket A or socket 370 users), in addition to making a fan adapter so it will work.
 

Jkasmann

Registered
Joined
Aug 16, 2002
Location
St Louis, MO
Not to mention variations between fans, ie fans like the TMD that are supposed to be more efficient for heatsinks (less dead area in the middle) and the channeled flow of delta and tornado fans. 30 CFM from one fan may not be the same as 30 CFM from another for heatsink use due variations in fan design.